What Is Fetal Development?
Healthy fetal development is crucial to a successful pregnancy and bringing your child into the world as healthy as possible. The goal of this page is to describe the development of the fetus at approximately 4-week intervals as well as the discuss the changes you will likely go through as your pregnancy progresses. During your appointments at Professionals for Women's Health, we can discuss many issues with you regarding your child's development. When you come in, please feel free to ask your provider any other questions you have about fetal development.
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4 Weeks
At this point, the embryo is less than a quarter-inch long. The first body segments develop, which will eventually become the brain and spinal cord. The heart, blood circulation, and digestive tract take shape, too. At this time, you miss your first period. Your breasts become tender and enlarged. Chronic fatigue and urinary frequency may begin, persisting for three or more months.
8 Weeks
The development of the embryo is rapid. The baby’s heart begins to pump blood and limb buds are well developed. Facial features and major divisions of the brain are discernible. The baby’s ears develop from skin folds; tiny bones and muscles are formed beneath the thin skin. By this time, the embryo has grown to nearly two inches in length. Morning sickness may persist for 12 weeks, and your uterus changes from pear to globular shape. You may notice an increase in vaginal discharge. Usually, there is no weight gain.
Depending on when you started our prenatal care, we will discuss alpha fetal protein (AFP) information with you between weeks 11-14.
12 Weeks
The embryo becomes a fetus. Its beating heart is discernible by Doppler. The baby assumes a more human shape as the lower body develops. The organs begin to differentiate, and the kidneys start to produce urine. His or her facial features and limbs become more distinct, and fingers, toes, ears, and eyelids are formed. The fetus weighs about one ounce and is three inches in length. Your uterus rises above the pelvic brim.
If you choose to have the AFP blood test to rule out birth defects involving the brain and spinal cord, it is done anytime between 16 and 18 weeks. This test is optional, and we discuss the pros and cons with you.
16 Weeks
The baby’s musculoskeletal system has matured, and his or her nervous system begins to exert control. Blood vessels rapidly develop. The baby’s fetal hands can grasp and the legs kick actively. The organs begin to mature and grow. At this point, the fetus weighs about seven ounces and is approximately six inches long. The fundus (top of uterus) is halfway between the pubis and navel.
You gain about one pound per week, and you may begin to feel more energetic. You may notice an increase in vaginal secretions and may begin wearing maternity clothes. The pressure on the mother’s bladder lessens, and urinary frequency decreases. You feel fetal movements (quickening) beginning between 16 and 22 weeks of gestation.
20 Weeks
The baby’s movements are stronger and more easily felt. The baby has grown to about 10 inches in length and weighs about a half-pound. Fine hair covers the body. The eyebrows, eyelashes and head hair develop. The fetus develops a regular schedule of sleeping, sucking and kicking. The fundus reaches the top of the navel. Your breasts may begin secreting colostrum.
An ultrasound is often done around 20 weeks. This ultrasound helps delineate fetal anatomy, placental position, and fluid volume. During your appointment around weeks 20-24, you will receive instructions about diabetic screening.
24 Weeks
The baby’s skin appears red and wrinkled. The baby’s skeleton develops rapidly as bone-forming cells increase. Respiratory movement begins. At this point, the fetus weighs about one pound, 10 ounces, or about 1.5 pounds. The fundus is above the navel. You may begin to have backaches and leg cramps, as well as changes in your skin and abdominal itching.
28 Weeks
The fetus can breathe, swallow, and regulate temperature. His or her eyes may occasionally open for short periods of time. At this time, the baby is 2/3 of its birth size. Your fundus is halfway between the navel and the breast bone. The fetal outline may be palpable. Parents begin taking childbirth preparation classes around this time. Additionally, blood is drawn for diabetic screening during your office visit around 28 weeks.
If you are Rh negative, you also have your antibody screen drawn. This day you will also receive your injection of RhoGam. At about 28 weeks gestation, your office visits become more frequent, from every four weeks to every two weeks.
32 Weeks
The baby is now almost fully grown, and movements are strong enough to be visible from the outside. The baby’s skin is no longer quite as wrinkled, and the baby is usually in the head-down position. Weight is around 4 pounds, and length is approximately 16.5 inches. The fundus reaches the bottom of the breast bone, and the mother’s breasts are full and tender. Urinary frequency may return. You may have swollen ankles and sleeping problems.
You will also receive your pre-admission form for the hospital in which you desire to deliver at. We suggest that you tour the labor and delivery units during this time.
36 Weeks
At 36 weeks gestation, you receive postpartum instructions. Your scheduled appointments change from every two weeks to every week. We discuss labor and delivery issues, including your hospital choice, your preference for anesthesia, and procedures for when you go into labor (when to call, etc.).
38 Weeks
The entire uterus is occupied by the baby, thus making its movement less pronounced. Maternal antibodies are being transferred to the baby. This provides immunity for about six months until the infant’s immune system can take over. The fetus descends deeper into your pelvis. The placenta is nearly four times as thick as it was 20 weeks ago. Backaches, urinary frequency, and Braxton Hicks contractions intensify as your cervix and lower uterine segment prepare for labor. Cervical checks begin to assess for dilation, effacement, and baby’s position.
Fetal development FAQs
When does fetal development begin?
The union of an egg and a sperm is the first step in a complex series of steps that lead to pregnancy. Once fertilization takes place, the fertilized egg begins to divide and grow. The small cluster of cells then moves through the fallopian tube to the uterus. Generally, a baby-to-be isn't considered a fetus until the ninth week after conception.
How will my uterus change during pregnancy?
The lining of the uterus thickens during pregnancy in order to support the growing baby. The muscles also become thicker and stronger to help push the baby out during labor. Professionals for Women's Health in Columbus, OH can help you understand how your uterus changes during fetal development when you come in for an initial appointment.
What is my estimated due date?
The estimated due date (EDD) is simply a calculation that takes into account the first day of your last menstrual period and the average length of a woman's menstrual cycle. The EDD is not necessarily set in stone, but it can be helpful for determining certain aspects of your prenatal care. Our team in Columbus, OH, can provide you with more information about your specific due date.
When does a pregnancy actually start?
Interestingly, a pregnancy is considered to start on the first day of your last menstrual period (LMP). This date is crucial for determining your due date and the gestational age of the fetus. Conception occurs about two weeks after this date.
How long is a typical pregnancy?
While we often think of pregnancy as lasting nine months, it can range from nine to ten months, totaling about 40 weeks or 280 days. This variation depends on the months during which the pregnancy occurs and the specific week of delivery.
Which weeks are most crucial for fetal development?
The first 13 weeks, or the first trimester, are considered the most critical for fetal development. During this phase, the fetus's major organs and systems form, and the risk of miscarriage significantly decreases after this period. However, it's essential to remember that every stage of pregnancy is important for the baby's health and development.
Providing top-notch care for your developing baby
Professionals for Women's Health understands the importance of your pregnancy journey and is here to answer any questions you may have about fetal development. Contact us to learn more and schedule an initial appointment with our gynecology team. We look forward to providing comprehensive care and support as you prepare for the arrival of your little one. From prenatal through postpartum care, we are here to help you each step of the way.