At 15 weeks gestation, the baby is no longer considered an embryo but rather a fetus. This is a crucial milestone in the pregnancy journey, as the fetus is rapidly growing and developing. Many exciting changes occur during this week that will continue to shape the baby’s future.
By the 15th week, the fetus is about the size of an apple, measuring around 4 inches in length and weighing about 2.5 ounces. Its body is becoming more proportional, with the head now being about one-third the size of the entire body. This growth spurt is accompanied by the development of more distinct facial features, including ears, eyelids, and eyebrows.
The fetus is also becoming more active at 15 weeks. Although the mother may not feel the movements yet, the baby is constantly kicking and moving its limbs. These movements are crucial for strengthening muscles and developing coordination. The baby is also practicing swallowing, as the digestive system is maturing in preparation for oral intake after birth.
Furthermore, the baby’s reproductive organs are now fully formed, allowing the parents to find out the baby’s gender through an ultrasound scan. The circulatory system is also becoming more complex, with the heart pumping about 26 quarts of blood per day. The bones are hardening, and tiny tooth buds are starting to develop beneath the gums.
Overall, the 15-week mark is an exciting time in the pregnancy journey. The baby is rapidly growing, gaining weight, and developing new skills. As the weeks progress, the fetus will continue to reach new milestones, bringing the parents closer to meeting their precious bundle of joy.
Embryonic Development at 15 Weeks
At 15 weeks gestation, the unborn fetus has reached an important milestone in its development. It is now considered a 15-week-old embryo, and its growth and development are continuing at a rapid pace.
Physical Development
By this stage of pregnancy, the unborn fetus has grown to be about the size of an apple, measuring around 4 inches long from head to bottom. Its tiny limbs are becoming more defined, and it is now capable of making small movements, although these movements may not yet be felt by the mother.
The facial features are also becoming more distinct, with the eyes and ears moving towards their final positions on the face. The unborn fetus can even suck its thumb, and its taste buds are developing, allowing it to taste the amniotic fluid surrounding it.
Organ Development
The internal organs of the 15-week-old embryo continue to mature and develop. The kidneys are now functioning, producing urine that is being expelled into the amniotic fluid. The intestines are also developing and moving into the abdomen.
The liver is producing bile, and the spleen is starting to help in the production of red blood cells. The lungs are still not fully developed, but the air sacs begin to branch out in preparation for future respiration.
The reproductive organs are also forming, although it may still be too early to determine the sex of the unborn fetus through ultrasound.
Emotional Development
While it is difficult to measure emotional development in an unborn fetus, studies suggest that by 15 weeks of gestation, the unborn fetus may be capable of experiencing emotions such as joy and sadness. The development of the limbic system, which is responsible for emotions, is underway.
Overall, the 15-week-old embryo is progressing steadily in its growth and development. The organs are maturing, and the physical features are becoming more evident. As the pregnancy moves forward, the unborn fetus will continue to grow and reach new milestones on its journey towards birth.
Growth and Changes
During the 15th week of gestation, the baby continues to grow and develop in the womb. At this stage, the fetus is about 15 weeks old and measures around 4 inches in length. Although still tiny, the baby is becoming more active and its movements can be felt by the mother.
The baby’s organs and body systems are also undergoing significant changes during this time. The skeletal system is beginning to harden as bones become more solid. The baby’s skin is developing a protective layer called vernix, which helps to keep the skin hydrated. The hair and nails are starting to grow, and the baby’s facial features are becoming more defined.
Additionally, the baby’s brain is going through rapid development. Nerve cells are forming connections, allowing the baby to practice reflexes like swallowing and sucking. The auditory system is also developing, and the baby may start to react to external sounds.
Size and weight
At 15 weeks, the unborn baby weighs around 2.5 ounces (70 grams) and is about the size of an apple. Despite its small size, the baby is growing rapidly and gaining weight steadily.
Movement
By 15 weeks, the baby’s movements are becoming more coordinated and purposeful. The mother may start to feel fluttering sensations, commonly referred to as “quickening,” as the baby kicks and stretches inside the womb. These movements are an exciting milestone in the pregnancy journey.
The baby’s movements can also be seen on ultrasound scans, allowing parents to witness their little one’s activity. Ultrasound images may show the fetus yawning, sucking its thumb, or even making small facial expressions.
Gestation | Week | Baby |
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15 weeks | 15 | Fetus |
Overall, the 15-week mark is an exciting time in pregnancy, as the baby continues to grow and develop. It’s important for expectant parents to take care of themselves and their baby by following a healthy lifestyle and attending regular prenatal check-ups.
Development of the Nervous System
At 15 weeks gestation, the unborn baby’s nervous system is rapidly developing. The nervous system, which includes the brain and spinal cord, plays a crucial role in controlling various bodily functions and development.
During this stage of pregnancy, the baby’s brain is undergoing significant growth and development. The brain cells, known as neurons, are forming intricate connections with each other, allowing for complex communication within the nervous system.
The baby’s spinal cord, which runs down the length of the back, is also developing. The spinal cord helps transmit signals between the brain and the rest of the body, allowing for movement and sensory perception.
As the nervous system continues to develop, the baby’s reflexes also begin to emerge. These reflexes, such as sucking and grasping, are crucial for survival and will continue to refine as the pregnancy progresses.
Furthermore, the baby’s sense of touch is developing as the nervous system continues to mature. The nerve endings in the skin send information to the brain, allowing the baby to experience sensation and respond to external stimuli.
Development of the Nervous System at 15 Weeks |
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Brain cells (neurons) are forming connections |
Spinal cord is developing |
Reflexes begin to emerge |
Improved sense of touch |
Overall, the 15-week-old fetus is going through a crucial stage of nervous system development, which will continue throughout the remainder of the pregnancy. Each milestone achieved in the development of the nervous system brings the baby closer to being able to interact with the world outside the womb.
Formation of Organs and Structures
At 15 weeks into pregnancy, the embryo has developed into a fetus, and remarkable progress continues to take place. During this week, the baby is approximately the size of a large orange.
At this stage of gestation, the organs and structures are forming rapidly. The baby’s bones are beginning to harden and the skeletal system is developing. The brain is growing rapidly, and the fetus is beginning to exhibit primitive reflexes, such as swallowing and sucking. The heart is fully formed and beating at a regular rhythm, pumping blood throughout the tiny body.
The eyes, ears, nose, and mouth are also developing, and the facial features become more distinct. The baby’s skin is still translucent and thin, but with each passing week, it becomes thicker and less transparent. Hair and nails are starting to grow, and the baby may even have peach fuzz on its skin. The limbs are becoming more proportionate, and the baby can move its arms and legs.
Inside the tiny body, the organs are forming and functioning. The kidneys are producing urine, and the liver is starting to produce bile. The intestines, which have been growing inside the umbilical cord, are now moving into the abdomen. The reproductive organs are also developing, although it may still be too early to determine the baby’s sex through ultrasound.
Overall, at 15 weeks, the unborn baby is rapidly developing and taking on the characteristics of a fully formed human being. The formation of organs and structures is a crucial stage in the baby’s development, laying the foundation for further growth and refinement in the upcoming weeks.
Sensory Development
During the 15th week of gestation, an unborn baby’s sensory development continues to progress. While still in the early stages, the fetus is starting to develop its sense of touch, taste, and hearing.
Touch
The baby’s skin is becoming more sensitive as it develops a layer of fatty tissue known as vernix caseosa, which protects the skin from the amniotic fluid. The fetus is now able to feel the gentle touch of its own body and may even respond to external touches or pressure applied to the mother’s abdomen.
Taste
The taste buds are beginning to form on the baby’s tongue, and the fetus can now taste some of the flavors of the amniotic fluid. If the mother eats different foods, the flavors can be detected by the baby. This is an early introduction to different tastes and can potentially influence the baby’s taste preferences later in life.
Hearing
The inner ear continues to develop, and the fetus can now hear sounds from inside and outside the womb. The baby’s hearing is more refined, and it can recognize and respond to familiar sounds, such as the mother’s voice or familiar music. Loud or sudden noises may startle the baby, causing it to move or kick in response.
It’s important to note that although the baby’s senses are developing, its experiences are limited to the womb environment. The mother’s activities, such as talking, singing, or playing soothing music, can help stimulate the baby’s senses and provide a comforting environment.
Development | Week |
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Sensory Development | 15 |
Ability to Hear and Respond
At 15 weeks of gestation, the embryo is now considered a fetus. During this week, the unborn baby’s ears continue to develop, allowing them to hear sounds from the outside world. While the fetus’s hearing is still developing, they can already respond to certain sounds and vibrations.
The ability to hear and respond is an important milestone in the 15-week fetus’s development. Although their hearing is still limited, the fetus can detect sounds such as the mother’s heartbeat, blood flowing through the umbilical cord, and even the mother’s voice. These sounds provide a sense of comfort and familiarity to the unborn baby.
Research has shown that the fetus’s heart rate may increase or decrease in response to different sounds, indicating that they can hear and respond to auditory stimuli. Studies also suggest that the fetus may develop a preference for certain sounds or voices, indicating their ability to recognize familiar sounds.
It is important for expectant mothers to be mindful of the sounds and noises around them as the 15-week fetus can now hear and respond. Talking or singing to the unborn baby can establish a bond between the mother and the unborn child. Playing soothing music or engaging in calming activities can also have a positive impact on the fetus’s development.
While the ability to hear and respond is still in the early stages, it is an exciting milestone in the pregnancy journey. It is a reminder that the unborn baby is developing rapidly and becoming more aware of the world around them.
Limbs and Movement
At 15 weeks of pregnancy, the unborn fetus is now considered an embryo. During this stage of gestation, the limbs of the embryo continue to grow and develop. The arms and legs become more defined, with the fingers and toes starting to form. This marks an exciting milestone as the baby’s movements become more coordinated.
The development of limbs and movement is crucial for the overall development of the fetus. As the arms and legs grow, they enable the baby to flex and move them. This movement is essential for the proper development of muscles and bones.
The 15-week fetus begins to make movements, although the mother may not be able to feel them yet. These movements, known as quickening, are important for the development of muscle strength and coordination. Although the movements are still small and uncoordinated at this stage, they will become more pronounced as the pregnancy progresses.
It is important to note that every fetus develops at its own pace, and not all mothers will feel the baby’s movements at 15 weeks. However, as the limbs continue to grow and the baby’s coordination improves, the movements will become more noticeable.
The development of limbs and movement in a 15-week fetus is a significant milestone in pregnancy. It signifies the growth and development of the baby’s arms, legs, and fingers, as well as the beginning of coordinated movement. This stage of development lays the foundation for future motor skills and physical activity.
As the pregnancy progresses, the baby’s movements will become more frequent and pronounced. Mothers may start to feel gentle flutters or kicks as the baby grows stronger. These movements are not only a sign of the baby’s development but also a source of joy and excitement for expectant parents.
Reflexes and Coordination
At 15 weeks of gestation, the embryo has now developed into a fetus and is in the midst of an important stage of pregnancy. During this week, several important milestones occur that contribute to the development of the baby’s reflexes and coordination.
The fetus’s movements become more coordinated during this stage, as its muscles continue to develop and strengthen. It may start to exhibit purposeful movements, such as kicking its limbs or moving its arms and fingers. These movements are a sign that the baby’s nervous system is maturing and its reflexes are more pronounced.
One reflex that is typically present in 15-week-old fetuses is the grasp reflex. This reflex allows the baby to automatically close its hand around an object that touches its palm. This reflex is an important precursor to the development of fine motor skills, as it helps the baby learn to hold and manipulate objects.
Another reflex that may be observed in a 15-week-old fetus is the startle reflex. This reflex is triggered by a sudden loud noise or a sudden movement, causing the baby to make a jerking motion. It is believed that this reflex helps the baby develop a sense of awareness and self-protection.
In addition to these reflexes, the fetus also begins to exhibit coordinated movements of its facial muscles. It may start to make facial expressions, such as opening and closing its mouth or furrowing its brow. These movements are an early indication of the baby’s ability to express emotions and respond to stimuli.
Importance of Early Reflexes
It is important for the fetus to develop and exhibit reflexes at this stage of pregnancy, as they are crucial for the baby’s survival and future development. Reflexes help the baby respond to its environment and protect itself from potential harm. They also serve as building blocks for the development of more complex motor skills and coordination later in life.
Parents and healthcare providers can monitor the baby’s reflexes during prenatal check-ups to ensure that their development is progressing normally. Any concerns or abnormalities in reflexes should be discussed with a healthcare professional to rule out any underlying issues that may require further attention or intervention.
Overall, the 15-week fetus is gradually becoming more coordinated and demonstrating the development of important reflexes. These early movements and reflexes lay the foundation for future motor skills and coordination as the baby continues to grow and develop.
Development of the Heart
The heart is a vital organ that plays a crucial role in the development of an embryo. By the 15th week of gestation, the unborn baby’s heart has undergone significant changes and is starting to resemble the structure of a fully formed heart.
During the early weeks of pregnancy, the embryo’s heart begins to form and develops into a primitive tube-like structure. This structure then starts to loop and fold, which eventually leads to the formation of the four chambers of the heart: the left and right atria and the left and right ventricles.
As the fetus continues to grow, the heart also undergoes further development. At around 15 weeks, the heart begins to beat at a regular rhythm, pumping blood throughout the tiny body. This is a significant milestone in the development of the cardiovascular system.
The heart’s development is a complex process that involves the formation of various cardiac structures, such as valves and blood vessels. The heart is responsible for supplying oxygenated blood to the baby’s body and removing waste products. It is truly a remarkable organ that ensures the baby’s survival and well-being during pregnancy.
Throughout the rest of the pregnancy, the heart will continue to mature and strengthen, preparing the baby for life outside the womb. While still small and delicate, the 15-week fetus’s heart is functioning and contributing to the overall growth and development of the baby. It is an incredible reminder of the miracles of life.
Development of the Respiratory System
During the 15th week of gestation, the respiratory system of the unborn baby continues to develop. The respiratory system is vital for the baby’s survival outside the womb, as it allows oxygen to enter the body and carbon dioxide to be expelled.
At this stage, the embryo is now considered a fetus, and its lungs are rapidly maturing. The lungs begin to produce a substance called surfactant, which is essential for the proper functioning of the air sacs or alveoli.
Formation of Air Sac
The formation of air sacs, which are responsible for the exchange of oxygen and carbon dioxide, starts during the 15th week. These air sacs will continue to develop and divide into smaller sacs as the pregnancy progresses.
Movement of the Diaphragm
The diaphragm, a thin muscle separating the chest cavity from the abdominal cavity, starts to contract and relax, allowing the baby to practice breathing movements. These practice breaths are essential for the development and strengthening of the respiratory muscles.
The respiratory system development plays a crucial role in preparing the baby for life outside the womb. Although the baby’s lungs are not fully developed at 15 weeks, this stage marks an important milestone in their journey towards breathing independently.
Development | Week |
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Embryo to Fetus | 15 |
Development of the Digestive System
During the 15th week of pregnancy, the baby’s digestive system continues to develop and mature. The growing embryo, now known as a fetus, is approximately 4 inches long and weighs about 2.5 ounces. At this stage, the digestive system is starting to take shape, although it is not yet fully functional.
Formation of the Digestive System
In the early weeks of pregnancy, the digestive system begins to form as a tube-like structure that runs from the mouth to the anus. This structure will eventually become the gastrointestinal tract, which is responsible for processing and absorbing nutrients from food.
During the 15th week, the fetus’s digestive system starts to become more complex. The intestines, which were previously coiled in the umbilical cord, are now relocating into the abdominal cavity. The intestines also begin to differentiate into the small intestine and the large intestine.
The liver, pancreas, and gallbladder, which play vital roles in digestion, are also developing during this stage. The liver starts producing bile, a substance that helps break down fats, while the pancreas begins to secrete digestive enzymes.
Maturation of the Digestive System
Although the digestive system is developing rapidly at 15 weeks, it is still not fully functional. The fetus is not yet capable of digesting food since the digestive organs are not yet fully formed. The baby continues to receive nutrition through the umbilical cord, which provides a direct supply of nutrients from the mother’s bloodstream.
As the pregnancy progresses, the digestive system will continue to mature. By the time the baby is born, the gastrointestinal tract should be fully formed, and the newborn will be able to process and digest breast milk or formula.
It is important for the mother to take care of her own digestive health during pregnancy to ensure the baby’s well-being. Eating a balanced diet, staying hydrated, and maintaining regular bowel movements can help support the development of a healthy digestive system in the unborn baby.
Formation of the Genitals
During the 15th week of pregnancy, the unborn baby, also known as an embryo, continues its development in the mother’s womb. This crucial stage of gestation marks the formation of the genitals, which will determine the baby’s gender.
By the 15th week, the baby’s genitalia begins to differentiate, and external male or female genitalia may start to become visible on an ultrasound scan. However, it is important to note that the accuracy of gender determination during this stage may vary.
It is fascinating to witness the transformation happening inside the womb as the baby’s reproductive system develops. The genitals, which were initially undifferentiated, begin to take shape, with the ovaries or testes beginning to form. For a female baby, the uterus and fallopian tubes also start to develop.
This stage of genital formation is crucial and lays the foundation for the baby’s future reproductive capabilities. It is important to remember that the baby’s gender is determined at the moment of conception, and the development at 15 weeks is simply the outward manifestation of that determination.
As the baby continues to grow and develop, parents and healthcare professionals eagerly anticipate the moment when the baby’s gender can be clearly determined. The formation of the genitals is an exciting milestone in the 15-week journey of pregnancy, bringing parents one step closer to meeting their precious bundle of joy.
Development of the Skeletal System
During the 15th week of pregnancy, the embryo has fully transformed into a fetus. At this stage of gestation, the unborn baby’s skeletal system is beginning to develop and take shape. The process of bone formation, also known as ossification, starts around the 6th week of pregnancy and continues throughout the fetal period.
The skeletal system plays a crucial role in supporting and protecting the developing fetus. It provides structure, allowing for the formation of the baby’s body and organs. The bones also act as a storage site for minerals like calcium and phosphate, which are essential for their growth and function.
By the 15th week, the fetus’s bones are becoming more defined and are gradually hardening. The long bones, such as those in the arms and legs, are elongating and developing their distinctive shape. The bones in the skull are also forming, with the process of fontanelle closure starting to occur. Fontanelles are the soft spots on a baby’s head that allow for flexibility during childbirth.
The fetal skeleton is primarily made up of cartilage, a flexible connective tissue that serves as a precursor to bone. During the 15th week, this cartilage starts to transform into actual bone through the process of ossification. The bones will continue to strengthen and harden as the pregnancy progresses.
The development of a healthy skeletal system is crucial for the overall growth and well-being of the unborn baby. It is important for pregnant individuals to maintain a balanced diet that includes adequate amounts of calcium, vitamin D, and other essential nutrients to support proper bone development.
Development of the Skeletal System at 15 Weeks |
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The long bones, such as those in the arms and legs, are elongating and developing their distinctive shape. |
The bones in the skull are forming, with the process of fontanelle closure starting to occur. |
The cartilage is transforming into actual bone through ossification. |
Overall, the development of the skeletal system at 15 weeks is a significant milestone in the fetal development process. It marks the beginning of bone formation and lays the foundation for the baby’s future growth and movement capabilities.
Development of the Muscular System
The muscular system of a fetus undergoes significant development during the 15th week of pregnancy. At this stage, the fetus is considered to be 15 weeks old and is growing rapidly. The muscles begin to form and multiply as the fetus continues to develop.
The muscles in the fetus play an important role in its movement and overall development. They enable the baby to make subtle movements and gestures, even though the mother may not be able to feel them yet. These movements are essential for the development of motor skills and coordination.
During this stage, the fetal muscles are still relatively weak and underdeveloped compared to a full-term baby. However, they continue to strengthen as the pregnancy progresses and the baby’s growth accelerates. By the end of the 15th week, the muscles are becoming more defined and can contribute to various movements.
The development of the muscular system is a complex process that involves the growth and differentiation of muscle cells. These cells, known as myocytes, multiply and fuse together to form muscle fibers. The fibers then organize into bundles and attach to bones, allowing the fetus to move its limbs.
As the muscular system develops, the fetus starts to exhibit more purposeful movements. It can flex and extend its limbs, rotate its head, and even make grasping motions. These movements are not only crucial for the development of the muscles but also provide the fetus with sensory feedback, helping it refine its motor skills.
It’s important to note that the development of the muscular system varies among individual fetuses. While some may exhibit more advanced movements at 15 weeks, others may still be in the early stages of muscle development. Each pregnancy is unique, and it’s important to consult with a healthcare professional for specific information about your baby’s development.
Overall, the 15th week of pregnancy marks a significant milestone in the development of the muscular system for an unborn baby. The muscles are beginning to form and strengthen, preparing the fetus for further growth and movement in the coming weeks and months.
Placenta and Umbilical Cord
The placenta and umbilical cord are vital structures that support the unborn baby throughout gestation. They play crucial roles in delivering oxygen, nutrients, and waste products between the mother and the developing embryo. By the 15th week of pregnancy, the placenta is fully formed and functioning.
The placenta is an organ that develops during pregnancy and attaches to the lining of the uterus. It acts as a lifeline for the baby, allowing it to receive all the essential nutrients and oxygen it needs to grow and develop. The placenta also filters out waste products, such as carbon dioxide, from the baby’s blood.
The umbilical cord connects the baby to the placenta. It contains blood vessels that carry oxygen-rich blood from the placenta to the baby and return oxygen-depleted blood back to the placenta. The umbilical cord also transports nutrients and hormones necessary for the baby’s development.
As the fetus continues to grow, the placenta and umbilical cord increase in size and efficiency to meet the baby’s increasing needs. They continue to provide a vital lifeline for the baby until birth when the umbilical cord is cut.
In summary, the placenta and umbilical cord are crucial for the development and well-being of the unborn baby. They work together to deliver oxygen, nutrients, and remove waste products throughout the baby’s growth during the 15th week of pregnancy. These structures play a vital role in ensuring a healthy pregnancy and fetal development.
Fetal Movement and Kicking
During the 15-week gestation period of pregnancy, the fetus has reached a significant stage of development. At this point, the embryo has transformed into a fully formed and recognizable unborn baby. One exciting milestone that occurs around this time is the onset of fetal movement and kicking.
As the nervous system continues to develop, the 15-week fetus becomes more active and responsive to its surroundings. This newfound energy translates into the ability to make small movements and even kick. While the movements may still be gentle, they are an indication of the growing strength and coordination of the developing muscles.
The pregnant mother may begin to feel these movements, commonly referred to as quickening, around this time. Initially, the sensations may be subtle and easy to miss, feeling like a gentle flutter or bubbles in the abdomen. However, as the fetus grows and gains strength, the movements will become more pronounced and easier to identify.
Feeling the baby move for the first time is often an exciting milestone for expectant parents. It provides a tangible connection to the unborn baby and can be a source of comfort and reassurance. It also serves as a reminder of the developing life within the womb, and the miraculous process of pregnancy.
It’s important to note that every pregnancy is unique, and the timing of fetal movement can vary. Some women may feel their baby move earlier or later than the 15-week mark. If there are concerns about fetal movement or if a pregnant woman is not feeling any movement, it is always best to consult with a healthcare provider to ensure the wellbeing of both the mother and the unborn baby.
Throughout the 15-week gestation period, the 15-week fetus continues to grow and develop, preparing for the next stages of pregnancy. The experience of feeling the baby move and kick is just one of the many incredible milestones along this journey of pregnancy.
Changes in the Mother’s Body
During the 15th week of pregnancy, the mother’s body continues to undergo changes to accommodate the growing baby. The uterus is now about the size of a small melon and can be felt above the pubic bone. As the baby grows, the mother may also experience round ligament pain, which is a sharp, shooting pain in the lower abdomen or groin area.
The mother’s breasts may also undergo changes during this time. They may become larger, more tender, and the nipples may darken in color. This is due to hormonal changes in preparation for breastfeeding.
The mother may also notice changes in her skin, such as the appearance of a linea nigra, which is a dark line that runs from the belly button to the pubic bone. Stretch marks may also start to appear on the abdomen, breasts, and thighs.
Additionally, the mother may experience changes in her energy levels and emotions. Some women may feel more energetic and have a renewed sense of well-being, while others may feel more tired and emotional due to hormonal fluctuations.
It is important for the mother to continue taking care of herself during this time. This includes eating a well-balanced diet, getting regular exercise, and getting plenty of rest. The mother should also continue to attend prenatal appointments and communicate with her healthcare provider about any concerns or changes she may be experiencing.