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 login to view 4 more bullets Timing initial prenatal visit at 8-10 weeks of pregnancy login to view 1 more bullet subsequent prenatal visits login to view 3 more bullets Initial prenatal visit assessment login to view 8 more bullets education/counseling login to view 8 more bullets routine lab/diagnostic studies login to view 30 more bullets Subsequent prenatal visits every visit login to view 7 more bullets weeks 11-14 of pregnancy login to view 4 more bullets weeks 15-20 of pregnancy login to view 3 more bullets weeks 24-28 of pregnancy login to view 4 more bullets weeks 32-34 of pregnancy login to view 2 more bullets week 36 of pregnancy login to view 2 more bullets week 38 of pregnancy login to view 2 more bullets > 41 weeks of pregnancy login to view 1 more bullet 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