What are the guidelines for prenatal care?

Prenatal Care Guidelines

For uncomplicated, low-risk pregnancies, follow the standard schedule of monthly visits until 28 weeks' gestation, biweekly visits from 28-36 weeks, and weekly visits from 36 weeks until delivery, with care ideally initiated before 10 weeks' gestation. 1

Standard Visit Schedule for Low-Risk Pregnancies

The traditional prenatal care schedule, established in 1930 and maintained through current 2017 guidelines, recommends 12-14 total visits structured as follows: 2

• Monthly visits from initial presentation through 28 weeks' gestation to monitor maternal health, screen for gestational diabetes, and assess fetal growth 1
• Biweekly visits from 28-36 weeks' gestation to increase surveillance as pregnancy advances and complication risks rise 1
• Weekly visits from 36 weeks until delivery to monitor for signs of labor, assess fetal well-being, and detect late-developing complications 1

International Context and Alternative Models

While U.S. guidelines recommend 13 visits (median 12-14), peer countries with superior maternal outcomes recommend significantly fewer visits: France and the Netherlands recommend 7.5 visits, the United Kingdom recommends 9 visits, and Sweden recommends 10 visits. 2 Most countries (6 of 9) recommend that low-risk women receive care exclusively from general practitioners or midwives rather than obstetrician-gynecologists. 3 The U.S. and Canada uniquely offer patients the option to choose between obstetrician-gynecologists, general practitioners, or midwives. 3

Timing of Care Initiation

Prenatal care should begin at 10 weeks' gestation or earlier to optimize outcomes, as early initiation is associated with fewer hospital admissions, improved education, greater satisfaction, and lower pregnancy-associated morbidity and mortality. 4 Early care is particularly vital for medically vulnerable and underserved populations, who are less likely to begin prenatal care in the first trimester. 5

Common Barriers to Early Care

Patients frequently delay care due to: being in transition (21%), unplanned pregnancy (17%), linkage-to-care issues including no-shows or cancellations (15%), recent relocation (8%), and difficulty scheduling within the first trimester (9%). 6 Spanish-speaking patients, younger patients, and those experiencing long delays between pregnancy confirmation and care entry are at highest risk for delayed initiation. 6

Critical Screening and Intervention Timepoints

First Trimester (Before 13 Weeks)

• Initiate care by 10 weeks or earlier for optimal outcomes 4
• Screen for asymptomatic bacteriuria, sexually transmitted infections, rubella and varicella immunity 4
• Obtain baseline laboratory tests including complete blood count to identify iron deficiency anemia 4
• Screen high-risk women for gestational diabetes at 12-14 weeks (those with BMI ≥30 kg/m² or prior gestational diabetes) 1
• Begin low-dose aspirin (81 mg daily) at 12 weeks for patients at risk of preeclampsia, including those diagnosed with COVID-19 in pregnancy 4
• Prescribe folic acid supplementation (400-800 mcg daily) to decrease neural tube defect risk 4
• Conduct ancestry-based genetic risk stratification using family history 4

Second Trimester (14-27 Weeks)

• Anatomy ultrasound at 18-20 weeks to evaluate fetal structure and development 1
• Universal gestational diabetes screening at 24-28 weeks for all women not previously diagnosed 1
• Repeat gestational diabetes screening at 24-28 weeks in high-risk women who initially tested negative 1
• Identify and treat periodontal disease to decrease preterm delivery risk 4

Third Trimester (28 Weeks to Delivery)

• Group B Streptococcus testing between 36-37 weeks with intrapartum antibiotic prophylaxis to decrease neonatal infection risk 4
• Administer tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine 4
• Ensure influenza and COVID-19 vaccination 4

Modified Schedules for High-Risk Conditions

High-risk pregnancies require intensified surveillance beyond the standard schedule:

• At preeclampsia diagnosis: immediate fetal biometry, amniotic fluid assessment, and Doppler studies 1
• Serial ultrasound every 2 weeks minimum for fetal growth, amniotic fluid, and umbilical artery Doppler from 24 weeks until birth in confirmed preeclampsia 1
• Weekly or twice-weekly antenatal surveillance at 32-34 weeks for most high-risk conditions, though this frequency lacks rigorous scientific evidence 1
• Biweekly ultrasound assessments minimum once fetal growth restriction is suspected or confirmed 1

Essential Clinical Considerations

Risk Factor Assessment

• Prepregnancy BMI >25 kg/m² is associated with gestational diabetes, hypertension, miscarriage, and stillbirth 4
• Advanced maternal or paternal age (≥35 years) is associated with gestational diabetes, hypertension, miscarriage, intrauterine growth restriction, aneuploidy, birth defects, and stillbirth 4
• Chronic hypertension should be treated to maintain blood pressure <140/90 mm Hg 4

Universal Psychosocial Screening

Screen early in pregnancy for depression, anxiety, intimate partner violence, substance use, and food insecurity, as social determinants of health significantly impact outcomes. 4

Important Caveats

• Routine antenatal testing does not improve outcomes in low-risk pregnancies and may cause iatrogenic prematurity from false-positive results 1
• No single antenatal test has proven superior for identifying fetuses at risk of intrauterine demise 1
• Antenatal surveillance cannot predict stillbirth from acute events such as placental abruption or cord accidents 1
• Failing to screen high-risk women early in pregnancy results in delayed intervention and increased complications 1
• Treatment of iron deficiency anemia decreases the risk of preterm delivery, intrauterine growth restriction, and perinatal depression 4
• Rho(D) immune globulin decreases alloimmunization risk in RhD-negative patients carrying RhD-positive fetuses 4