At the new OB appointment we take a detailed medical and family history and a physical exam including pap smear(if indicated), cultures, and blood work. Typical first trimester blood work includes a complete blood count (to look for anemia), blood type and antibody screen, rubella immunity test, screening for syphilis, hepatitis B and HIV. Also a screening urine culture is sent.
Genetic carrier screening. Cystic fibrosis and spinal muscular atrophy are two autosomal recessive diseases with known mutations that we can screen for. The risk to be a carrier for each condition varies by ethnicity. Genetic carrier screening is optional.
Prenatal screening or diagnostic testing for chromosome abnormalities or aneuploidy such as Down’s syndrome, trisomy 13 or trisomy 18 is also reviewed. Read our blog for more information about prenatal tests in the first trimester.
Non-invasive Prenatal Screening (NIPS): NIPS is a maternal blood test that analyzes fetal DNA fragments to determine the risk for Down syndrome, Trisomy 18, Trisomy 13, Triploidy and Turner syndrome.with a 97-99% detection rate. This is a screening test and does have 1% false positives. Also it is not checking all of the fetal chromosomes but looks at the abnormalities we see most often. If it comes back “high risk” then diagnostic testing is recommended.
First trimester screening: This screening test involves an ultrasound and a maternal blood test done between 11-14 weeks to determine the risk for Down’s syndrome, trisomy 13 and trisomy 18. This detects 90-95% of these 3 chromosome mistakes with 5% false positives. The ultrasound measures the thickness of the fetal neck (nuchal translucency). A thickened nuchal fold can also be associated with cardiac defects.
Diagnostic testing is offered to “high risk” patients such as women over age 35, women with abnormal NIPS or screening test or women with a baby that has anomies seen on ultrasound.
Chorionic villous sampling (CVS): The CVS procedure uses a needle to obtain a sample from the placenta under ultrasound guidance between 10-13 weeks. The cells from the placenta are used to test the fetal chromosomes. There is a small increased risk of miscarriage estimated to be 1:200 or 0.5%.
Amniocentesis: The amniocentesis using a needle to remove some fluid from around the baby with ultrasound guidance between 15-20 weeks. Fetal cells are obtained from the fluid to do the chromosome testing. There is a smaller risk of miscarriage estimated to be 1:350.
- Alpha Fetal Protein (AFP). If desired, this is a blood test to screen for neural tube defects.
- Childbirth education classes. Classes usually start in the 6th or 7th month.
- A comprehensive ultrasound is done to look at the fetal anatomy to identify structural birth defects. Birth defects are present in 2-3% of live born infants. If a women is age 35 or older at delivery or there is a family history of birth defects then we refer to the high risk ob specialists for this detailed ultrasound.
- Blood work to check hemoglobin (iron levels) again, and to screen for gestational diabetes. You will drink a cola drink containing 50 grams of sugar (or eat 26 jelly beans) wait one hour, and then have your blood drawn to check sugar levels. We also check your urine for infection one more time.
- TDAP. Tdap is a vaccine against adult whooping cough. The mother creates antibodies against whooping cough, which cross the placenta and help protect the newborn. The amount of antibodies against whooping cough decreases quickly in adults, which is why women should be vaccinated during every pregnancy and not before. By breastfeeding you may pass some antibodies you have made in response to the vaccine to your baby. Your baby should have his or her first whooping cough vaccine (DTaP) at 2 months of age.
- Rhogam injection after negative antibody screen. We’ll do this test if you are Rh negative and the father of the baby is Rh positive.
- Group Beta Strep (GBS) vaginal/rectal culture. While GBS is normally present in the vagina and bowel of about 10-30% of women, we now know it can be dangerous for newborns. Accordingly, we check all women for GBS in the last month of pregnancy. If you are found to be a GBS carrier, we recommend treating you with antibiotics while you are in labor, in order to decrease the amount of bacteria the baby might be exposed to during delivery. Since Penicillin is our preferred antibiotic for GBS, please be sure to remind us if you are allergic to penicillin when we collect the culture.
- Your baby can come any time!!! If you have not delivered by 40 weeks, plan an ultrasound to check amniotic fluid levels and a non-stress test (NST) to be sure your baby is healthy. We repeat this testing twice during your final week 41-42.
Visits and common tests during pregnancy