Snapshot A 26-year-old G1P0 woman presents to the obstetrician for her first prenatal visit. An ultrasound is performed (See image). She is estimated to be approximately 8 weeks gestation. She notes that she has experienced increased fatigue and occassional nausea but no major complaints. The patient is a recent immigrant from Mexico and has no immunization records with her and does not recall her vaccination history. She is sexually active with only her husband and has no history of sexually transmitted infections. The obstetrician takes a thorough medical history, performs a physical examination, informs her about the course of pregnancy, and explains details of the laboratory studies that will be performed at the current visit and subsequent visits. Introduction Overview prenatal care helps to ensure the birth of a healthy baby while also maintaining a healthy pregnancy for the mother accurate estimation of gestational age identify pregnancies at ↑ risk for maternal or fetal morbidity/mortality prevent morbidity during pregnancy provide a transition to a healthy labor and birth Timing initial prenatal visit at 8-10 weeks of pregnancy earlier if at risk for ectopic pregnancy subsequent prenatal visits every 4 weeks for the first 28 weeks every 2-3 weeks until 36 weeks gestation every week after 36 weeks gestation Initial prenatal visit assessment initial history and physical exam family medical history genetic history general examination to confirm pregnancy assess for tobacco, alcohol, and/or drug use screen for domestic violence screen for depression provide prescriptions for prenatal vitamins and iron supplementation education/counseling inform about expected course of pregnancy discuss recommendation for 30 minutes of moderate-intensity exercise 5-7 days a week avoid contact sports or activities with high fall risk discuss routine lab studies and testing discuss genetic counseling and prenatal diagnostic testing cystic fibrosis carrier screening hemoglobinopathy screening for individuals of African, Southeast Asian and Mediterranean descent discuss high-risk conditions routine lab/diagnostic studies blood type and screen complete blood count (CBC) platelet count hepatitis B surface antigen (HBsAg) syphilis screening test screening for gestational diabetes if at high risk risk factors for gestational diabetes mellitus pre-pregnancy BMI ≥ 30 kg/m previous history of gestational diabetes HIV screening test cervical cancer screening Pap test urine dipstick for protein and glucose levels urine culture and sensitivity test asymptomatic bacteriuria should be treated in pregnant women chlamydia screening gonorrhea screening for women at risk for sexually transmitted infections risk factors for sexually transmitted infections age < 25 years previous sexually transmitted infection new or multiple sex partners inconsistent condom use commercial sex work rubella titer if not already immune, do not administer vaccine during pregnancy MMR (measles, mumps, and rubella) is a live vaccine TSH hypothyroid women should have their dose of levothyroxine increased if found to be pregnant during pregnancy, ↑ circulating levels of thyroxine-binding globulin (TBG), and ↑ plasma volume ↑ demand for T4 inactivated influenza vaccination Subsequent prenatal visits every visit vital signs weight fetal assessment, beginning after 10 weeks gestation uterine size assessment (see Table below) domestic violence screening assessment of tobacco use and exposure urine dipstick for protein and glucose levels weeks 11-14 of pregnancy education about breastfeeding screening tests for aneuploidy women with ↑ risk for aneuploidy offer option of chorionic villus sampling or 2nd trimester amniocentesis weeks 15-20 of pregnancy anatomic survey ultrasound at 18-20 weeks neural tube defect screening maternal serum alpha-fetoprotein (MSAFP) weeks 24-28 of pregnancy repeat type and screen if Rh negative, administer Rh immunoglobulin screen for gestational diabetes discuss postpartum contraception weeks 32-34 of pregnancy repeat testing for women at ↑ risk for sexually transmitted infections syphilis, HIV, gonorrhea, and chlamydia week 36 of pregnancy determine fetal position group B strep screening week 38 of pregnancy provide information about labor discuss postpartum contraception again > 41 weeks of pregnancy discuss labor induction Estimating Gestational Age by Uterine Size12 weeksAt pubic symphysis16 weeksMidway from symphysis to umbilicus20 weeksAt umbilicus20-36 weeksHeight (in cm) above pubic symphysis correlates with weeks of gestation Timing of Major Prenatal Tests Prental Test Gestational Age (Weeks) Details of test First trimester screen 11-14 Ultrasound for nuchal translucency PAPP-A ↓ levels are seen in chromosomal abnormalities hCG ↑ levels are seen in chromosomal abnormalities Cell free fetal DNA ~10 Analyze fetal DNA in maternal blood Screens for trisomies of 13, 18, and 21 Positive test results should be followed by CVS or amniocentesis Chorionic villus sampling (CVS) 11-14 Collect placental tissue to test for chromosomal and genetic abnormalities Quadruple screen 16-18 AFP, hCG, estriol, and inhibin ↑ AFP = neural tube or abdominal wall defects ↑ hCG and inhibin and↓ AFP and estriol = Down syndrome ↓ AFP, hCG, and estriol = Edwards syndrome Amniocentesis 15-20 Collect amniotic fluid to diagnosis chromosomal abnormalities Glucose challenge test 24-28 1 hr glucose challenge test If abnormal followed by glucose tolerance test Group B strep test 35-37 Swab the lower genital tract for colonization by GBS, treat with antibiotics during labor if the patient is positive