What is the recommended schedule and components of prenatal check-ups during pregnancy?

Prenatal Check-Up Schedule and Components

All pregnant women should initiate prenatal care by 10 weeks gestation or earlier, with comprehensive laboratory screening at the first visit including blood type/Rh status, complete blood count, infectious disease panel (HIV, syphilis, hepatitis B, rubella immunity), urinalysis with culture, and genetic screening based on risk factors. 1, 2, 3

First Trimester Visit (Ideally 8-12 Weeks)

Essential Laboratory Testing

• Blood type and antibody screen to identify Rh status and blood incompatibilities 2
• Complete blood count to detect anemia and establish baseline hematologic parameters 2
• Infectious disease screening: HIV (opt-out screening), syphilis serology, hepatitis B surface antigen, and rubella immunity status 1, 2
• Urinalysis and urine culture for asymptomatic bacteriuria screening 1, 2
• Fasting blood glucose in women with diabetes risk factors 2
• Cervical cytology if not documented within the preceding year 1

Genetic Screening and Counseling

• Ancestry-based genetic risk assessment using family history to inform carrier screening for conditions like cystic fibrosis 1, 3
• Cell-free DNA (noninvasive prenatal testing) should be offered as first-line screening for Down syndrome, with >99% detection rate 4
• Combined first-trimester screening (nuchal translucency at 11-13 weeks plus PAPP-A and β-hCG) achieves 85% Down syndrome detection at 5% false-positive rate 2

First Trimester Ultrasound (11-13 Weeks)

• Crown-rump length measurement provides gestational age accuracy within 7 days and is the gold standard for pregnancy dating 2, 5
• Nuchal translucency measurement between 11 weeks 0 days and 13 weeks 6 days for aneuploidy screening 2
• Chorionicity determination in twin pregnancies (nearly 100% accuracy in first trimester) 2

Nutritional Supplementation

• Folic acid 400-800 mcg daily for standard-risk women until 12 weeks to prevent neural tube defects 1, 2, 3
• Folic acid 5 mg daily for high-risk women (after checking vitamin B12 deficiency) 2
• Calcium supplementation (at least 1 g/day) for women with low calcium intake to reduce preeclampsia risk 1

Risk Assessment and Counseling

• Reproductive life plan discussion and pregnancy intentions 1
• Medication review to avoid FDA category X and most category D medications 1
• Substance use screening using CAGE or T-ACE questionnaires for alcohol and drug use 1
• Mental health screening for depression, anxiety, and intimate partner violence 3
• Food insecurity screening as part of social determinants of health assessment 3
• Periodontal disease assessment since treatment decreases preterm delivery risk 3

Second Trimester Visits

16-20 Week Visit

• Detailed anatomic ultrasound at 18-22 weeks for structural abnormalities 2
• Chlamydia screening in third trimester for women <25 years or with risk factors 1
• Gonorrhea screening repeat in third trimester for those at continued risk 1

24-28 Week Visit

• Gestational diabetes screening for all patients using 1-hour glucose challenge test or 2-hour oral glucose tolerance test 3, 5
• Repeat HIV testing in third trimester for high-risk women or in jurisdictions with elevated HIV incidence 1
• Repeat syphilis screening in third trimester for high-risk patients 1
• Repeat hepatitis B testing late in pregnancy for high-risk women who were initially negative 1

Third Trimester Visits

28-32 Week Visit

• Repeat complete blood count to assess for anemia 3
• Tdap vaccine administration between 27-36 weeks (ideally early in this window) 3, 5

36-37 Week Visit

• Group B Streptococcus screening via vaginal-rectal swab to guide intrapartum antibiotic prophylaxis 3

Ongoing Throughout Pregnancy

Immunizations

• Influenza vaccine during any trimester when available 3, 5
• COVID-19 vaccine as recommended 3
• Tdap vaccine between 27-36 weeks gestation 3, 5

Preeclampsia Prevention

• Low-dose aspirin 81 mg daily starting at 12-16 weeks for high-risk women (chronic hypertension, previous preeclampsia, diabetes, renal disease, autoimmune disease, multifetal gestation) 1, 3, 5

Blood Pressure Management

• Chronic hypertension treatment to maintain blood pressure <140/90 mm Hg 3

High-Risk Monitoring

• Fetal biometry, amniotic fluid assessment, and Doppler studies at diagnosis of preeclampsia, with serial evaluation every 2 weeks minimum 1
• Antenatal fetal surveillance (nonstress testing or biophysical profile) for high-risk conditions, typically initiated at 32-34 weeks with weekly or twice-weekly testing 1
• Umbilical artery Doppler velocimetry for intrauterine growth restriction secondary to uteroplacental insufficiency 1

Visit Frequency

Standard schedule: Monthly visits until 28 weeks, every 2 weeks from 28-36 weeks, then weekly until delivery 3, 5

Critical Timing Considerations

• Prenatal corticosteroids for fetal lung maturation between 24-34 weeks if preterm delivery anticipated 1
• Magnesium sulfate for fetal neuroprotection before 32 weeks if preterm delivery imminent 1
• Induction of labor offered at 41 weeks with recommendation for delivery before 42 weeks 5

Common Pitfalls to Avoid

• Do not perform elective delivery before 39 weeks without maternal or fetal indications 5
• Isolated soft markers on ultrasound have no clinical significance in patients with normal cell-free DNA screening and should not cause unwarranted anxiety 4
• Avoid labeling women >35 years as "high risk" based solely on age if screening tests are low-risk 4
• Do not delay HIV testing results - rapid testing should be performed in labor if no documentation exists, with immediate antiretroviral prophylaxis for reactive results 1