What is the standard protocol for OB-GYN (Obstetrics and Gynecology) prenatal care?

Standard OB-GYN Prenatal Care Protocol

Visit Schedule

For low-risk pregnancies, schedule 8-14 prenatal visits following this evidence-based timeline: initial visit by 10 weeks, then visits at 16,22,28,32,36,38,39, and 40 weeks gestation. 1

The traditional 12-14 visit schedule established in 1930 has remained largely unchanged, though recent evidence supports that reduced-visit models (8 visits) enhanced with remote monitoring are equally safe and result in higher patient satisfaction for low-risk pregnancies. 1, 2 High-risk pregnancies require more frequent monitoring with individualized schedules. 3

Initial Visit (Before 13 Weeks)

History and Risk Assessment

• Obtain complete medical history including reproductive history, previous pregnancy complications, chronic medical conditions (hypertension, diabetes, thyroid disease), current medications, and family history for genetic risk stratification. 4, 5
• Document reproductive life plan and assess for high-risk conditions requiring specialized care. 5
• Screen for psychosocial risk factors including housing insecurity, social support, intimate partner violence, and mental health concerns. 4, 5

Physical Examination

• Perform focused examination including periodontal assessment, thyroid palpation, cardiac auscultation, breast examination, and complete pelvic examination with cervical cytology if not performed within the preceding year. 4, 5, 3

Laboratory Testing

• Universal screening: Complete blood count, urinalysis, blood type and Rh screen, rubella immunity, hepatitis B surface antigen, syphilis (RPR/VDRL), HIV testing. 4, 5, 3
• Risk-based screening: Gonorrhea and chlamydia (all women under 25 or with risk factors), varicella immunity if unknown, thyroid-stimulating hormone for those with symptoms or risk factors. 5
• Genetic screening: Offer chromosomal screening based on family history, ethnic background, and maternal age. 4

Supplementation and Medications

• Prescribe prenatal vitamins containing 400-800 mcg folic acid and 150 mcg potassium iodide, ideally started preconception. 4, 5
• Review all medications for teratogenicity and discontinue ACE inhibitors, ARBs, and statins immediately. 4

Lifestyle Counseling

• Mandate complete avoidance of alcohol, tobacco, recreational drugs, hot tubs, and hyperthermia. 4, 5
• Recommend regular moderate exercise such as brisk walking, swimming, or prenatal yoga. 4, 5
• Promote balanced nutrition with "five-a-day" (2 servings fruit, 3 servings vegetables) and adequate hydration. 4, 5

Immunizations

• Administer influenza vaccine if pregnant during flu season and not previously vaccinated. 5
• Document immunization status for hepatitis B, rubella, and varicella. 5

Second Trimester Care (14-28 Weeks)

Preeclampsia Prevention

Initiate low-dose aspirin (81-150 mg daily) before 16 weeks gestation for women with major risk factors: previous preeclampsia, chronic hypertension, pregestational diabetes, BMI ≥35, chronic kidney disease, or antiphospholipid syndrome. 4, 5 Continue until 36 weeks gestation. 4

Fetal Anatomy Assessment

• Perform detailed fetal anatomy ultrasound between 16-22 weeks gestation to detect congenital anomalies. 4
• For women with pregestational diabetes, schedule fetal echocardiogram between 16-22 weeks. 4

Gestational Diabetes Screening

• Screen all women at 24-28 weeks using 1-hour glucose challenge test (50g) or 2-hour oral glucose tolerance test. 5, 3
• Women with risk factors (obesity, previous gestational diabetes, family history) should also be screened in the first trimester. 3

Tdap Vaccination

• Administer Tdap vaccine between 27-36 weeks gestation to provide infant protection against pertussis. 5

Third Trimester Care (28+ Weeks)

Monitoring Frequency

• Monitor blood pressure and assess for preeclampsia signs (new hypertension, proteinuria, headache, visual disturbances, epigastric pain, reduced fetal movements) at every visit after 20 weeks. 4
• Perform serial fetal growth evaluations every 4 weeks for patients with chronic hypertension or other high-risk conditions. 3

Antepartum Surveillance

• Initiate fetal surveillance at 32-34 weeks for high-risk pregnancies (diabetes, hypertension, suspected growth restriction). 5

Special Population: Pregestational Diabetes

Women with preexisting diabetes require intensive multidisciplinary management to achieve A1C <6.5% before conception, reducing congenital malformations from 1.4-10.9% to 1.0-1.7%. 4, 5

Team Composition

• Establish care with endocrinologist, maternal-fetal medicine specialist, registered dietitian, and diabetes educator. 4, 5, 3

Glucose Monitoring Targets

• Fasting glucose <95 mg/dL and either 1-hour postprandial <140 mg/dL or 2-hour postprandial <120 mg/dL. 4, 5, 3

Additional Surveillance

• Perform dilated eye examinations before pregnancy or in first trimester, then every trimester and for 1 year postpartum. 5
• Schedule fetal echocardiogram between 16-22 weeks. 4

Delivery Timing

• Plan delivery at 39 0/7 to 39 6/7 weeks with good glycemic control. 5, 3
• Deliver at 36 0/7 to 38 6/7 weeks with poor control or vascular complications. 5, 3

Critical Pitfalls to Avoid

• Inadequate preconception counseling for women with chronic conditions (diabetes, hypertension) significantly increases maternal and fetal complications. 5
• Delaying Tdap administration beyond 36 weeks or omitting it entirely leaves infants vulnerable to pertussis in early life. 5
• Unnecessary induction of labor for suspected fetal macrosomia does not improve maternal or fetal outcomes. 3
• Failure to prescribe low-dose aspirin before 16 weeks for high-risk women misses the critical window for preeclampsia prevention. 4
• Inadequate monitoring of high-risk conditions like diabetes and hypertension during pregnancy. 3