Understanding each stage of your pregnancy
While a full-term pregnancy lasts 40 weeks, there are many milestones along the way. Pregnancy is divided into three stages, known as trimesters. Week by week, each stage takes your baby one step closer to delivery. The obstetrician-gynecologists (OBGYNs) at Baylor Scott & White provide comprehensive, compassionate maternity care for every trimester of your pregnancy.
First trimester: Weeks 1 to 12
At your first routine maternal health checkup, your OBGYN will confirm whether you are pregnant and establish your due date. Your OBGYN will provide education to help you make healthy choices for your pregnancy. People with a typical pregnancy will see their OBGYN monthly during the first trimester.
Providers typically measure pregnancy in weeks, starting from the first day of your last menstrual period. Over the first 12 weeks, you release an egg, which is fertilized by sperm and implants in your uterus. The fertilized egg, a single cell, divides many times until it forms an embryo and then, at about 10 weeks, a fetus with facial features and a detectable heartbeat. By week 12, your fetus is about 3 inches long and weighs about an ounce.
Second trimester: Weeks 13 to 28
In the second trimester, you will continue to visit your OBGYN each month unless you need extra care. Your OBGYN will provide other tests you may need to keep you and your baby healthy. For instance, a diabetes test may influence their guidance for nutritious eating throughout pregnancy. Your OBGYN may also recommend that you receive certain vaccinations.
During this second stage of pregnancy, your baby develops rapidly. By week 28, your baby is about a foot long and may weigh up to 1.5 pounds. Their bones begin to harden, make blood cells, and move.
Third trimester: Weeks 29 to 40
Generally, checkups occur every two 2-3 weeks from week 28 through week 36, then weekly until your baby arrives. During these visits, your OBGYN will continue to monitor your baby’s health. They’ll discuss your birth plans with you and may offer resources such as childbirth and parenting classes, lactation consultation, and other services for you and your baby.
During the third trimester of pregnancy, your baby finishes growing and even begins to add fat. A full-term infant generally arrives between 39 and 40 weeks. Full-term babies may weigh between 6 and 9 pounds and be around 19 to 21 inches long.
Fourth trimester: After baby arrives
Many people describe the 12 weeks after birth as the fourth trimester of pregnancy. During this postpartum phase, your body continues to change as you recover from childbirth and many of the physical changes of pregnancy reverse.
Postpartum visits will occur, at minimum, within three weeks after birth and again at six weeks. Your OBGYN will check that you’re healing physically and monitor your mental well-being. Your OBGYN will also provide contraceptive guidance if you want it. If you experienced high blood pressure or gestational diabetes when you were pregnant, your OBGYN may perform a risk assessment and help you coordinate care for these conditions.
Moms who deliver at BSWH have access to Virtual Postpartum Care for comprehensive support during those first six months after delivery. You can speak directly to a Nurse Care Advocate for personalized guidance and access specialists for lactation support and pelvic floor therapy – all through convenient virtual services.
Rh factor
This blood test tells your doctor if you and your partner have Rh factor, a protein in red blood cells. If one of you does and one does not, you are considered Rh incompatible. In some cases, Rh incompatibility can increase certain risks, and the tests will help your OBGYN guide treatment decisions during pregnancy.
Ultrasounds
Ultrasounds are noninvasive tests that use sound waves to project an image. You may receive an ultrasound to check for a heartbeat during your first visit. Your baby is tiny at this stage, but ultrasounds at subsequent checkups help determine how quickly your baby grows, if there are multiples (such as twins) and the baby’s sex.
Amniocentesis
An amniocentesis tests your amniotic fluid, the liquid that surrounds and protects your growing baby in the womb. Performed between weeks 15 and 20, amniocentesis looks for signs of Down syndrome or open neural tube defects, such as spina bifida. This type of test is rare.
Alpha-fetoprotein (AFP) test
An AFP test is performed around 18 weeks into your pregnancy. This test measures AFP levels, a protein found in the baby's liver. The results of this test can tell if the baby has any genetic disorders or birth defects that affect the brain and spine, known as neural tube defects, including spina bifida.
Our pregnancy services
Routine testing is a big part of prenatal care. Your OBGYN will determine which tests you need based on your health history and the results of your prenatal care visits.
Noninvasive prenatal testing (NIPT)
NIPT is a blood test that typically happens around 11 weeks into the pregnancy. It analyzes the baby's DNA to screen for abnormalities or genetic defects, such as Down syndrome. This test was developed to replace chorionic villus sampling.
Glucose (blood sugar) screening
Glucose screenings can tell your doctor if you have or are at risk for gestational diabetes. The test is typically performed between 24 and 28 weeks unless urine samples show high blood sugar levels before then.
Find a location near you
You can find comprehensive pregnancy care at Baylor Scott & White locations throughout North and Central Texas.
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Virtual Postpartum Care
Postpartum care doesn't stop when you leave the hospital. With the Virtual Postpartum Care program, you'll have access to the support you need—all from the comfort of your home.
- Real-time guidance from healthcare providers
- Access to a nurse care advocate
- Resources from specialists, including lactation consultants and pelvic floor therapists