What are the recommended prenatal care and management guidelines for a healthy female in her third trimester of pregnancy with no significant medical history?

Third Trimester Prenatal Care for Healthy Pregnancy

For a healthy woman in her third trimester with no significant medical history, prenatal care should focus on routine fetal surveillance, screening for gestational diabetes and group B Streptococcus, monitoring for preeclampsia, and planning for delivery timing at 39-40 weeks. 1, 2

Routine Monitoring and Surveillance

Clinical Assessments

• Fundal height measurement at every visit using either customized growth charts or McDonald rule to screen for fetal growth abnormalities 3
• Blood pressure monitoring at every visit after 20 weeks to detect new-onset hypertension, proteinuria, headache, visual disturbances, epigastric pain, or reduced fetal movements as signs of preeclampsia 1
• Fetal movement awareness counseling should be provided, with instruction to report decreased movements 1

Laboratory Screening

• Group B Streptococcus screening between 36-37 weeks gestation with intrapartum antibiotic prophylaxis if positive to decrease neonatal infection risk 4
• Gestational diabetes screening between 24-28 weeks (if not already completed in second trimester) for all patients 3, 2, 4

Ultrasound Considerations

Routine third-trimester ultrasound scanning is NOT recommended for low-risk pregnancies as a screening tool for small-for-gestational-age fetuses 3. However, ultrasound should be performed if:

• Fundal height measurements suggest growth abnormalities 3
• Clinical concerns arise regarding fetal size or well-being 3
• Delivery planning requires fetal weight estimation near term 3

Immunizations

All pregnant women should receive:

• Tdap vaccine (tetanus toxoid, reduced diphtheria, acellular pertussis) ideally between 27-36 weeks of each pregnancy 2, 4
• Influenza vaccine if during flu season, regardless of trimester 2, 4
• COVID-19 vaccine as recommended 4

Infectious Disease Screening

HIV Testing

• HIV screening should have been completed early in pregnancy 3
• Retesting in third trimester (preferably before 36 weeks) is recommended for women at high risk, including those with history of sexually transmitted diseases, multiple sex partners during pregnancy, illicit drug use, or sex partners known to be HIV-positive 3
• Women admitted for labor with unknown HIV status should receive expedited testing with rapid results to allow timely prophylactic treatment 3

Sexually Transmitted Infections

• Repeat testing for gonorrhea and chlamydia in third trimester for women under 25 years or with new/multiple partners to prevent maternal postnatal complications and neonatal infection 3
• Syphilis screening at delivery is mandated in some states for all women, and recommended for high-risk women 3

Nutritional and Lifestyle Counseling

• Continue prenatal vitamins with folic acid throughout pregnancy 3, 1
• Promote balanced nutrition with five servings daily (2 fruits, 3 vegetables) 3, 1
• Encourage regular moderate exercise such as brisk walking, swimming, or prenatal yoga 1
• Counsel complete avoidance of alcohol, tobacco, and recreational drugs 1
• Screen for food insecurity, depression, anxiety, intimate partner violence, and substance use as social determinants significantly impact outcomes 4

Delivery Planning

Timing of Delivery

For uncomplicated pregnancies with good prenatal care:

• Do NOT offer elective delivery before 39 weeks 2
• Offer induction at 41 weeks with recommendation for delivery before 42 weeks 2
• Optimal delivery window is 39 0/7 to 39 6/7 weeks gestation 3

Mode of Delivery Considerations

• Ultrasound for fetal growth assessment should be performed near term if there are concerns about macrosomia 3
• Consider cesarean delivery if estimated fetal weight ≥4500 grams to reduce shoulder dystocia risk 3

Mental Health Screening

Universal screening for mental health conditions should occur at every consultation:

• Screen for depression and anxiety using validated tools 4
• Connect women to counseling or support groups as needed 1
• Recognize that perinatal mental health significantly impacts maternal and neonatal outcomes 4

Common Pitfalls to Avoid

• Do not perform routine serial ultrasounds in low-risk pregnancies as this is not evidence-based and increases healthcare costs without improving outcomes 3
• Do not delay group B Streptococcus screening beyond 37 weeks, as results may not be available before spontaneous labor 4
• Do not assume all third-trimester bleeding is benign - evaluate promptly for placental abruption or previa 5
• Do not miss opportunities for Tdap vaccination - it should be given in EVERY pregnancy between 27-36 weeks, regardless of prior vaccination history 2, 4

Special Circumstances Requiring Enhanced Surveillance

While this question addresses healthy women, clinicians should maintain vigilance for conditions that would necessitate modified care:

• New-onset hypertension or preeclampsia symptoms require immediate evaluation 1
• Decreased fetal movement requires same-day assessment 1
• Vaginal bleeding requires prompt evaluation to exclude placental complications 5
• Signs of preterm labor (regular contractions, cervical change before 37 weeks) require urgent assessment 5