What is prenatal care?

What is Prenatal Care?

Prenatal care is a comprehensive system of medical and psychosocial services provided throughout pregnancy—encompassing antepartum, intrapartum, and postpartum periods—designed to monitor maternal and fetal health, identify and manage risks, and ultimately reduce maternal and infant morbidity and mortality. 1

Core Components of Prenatal Care

Prenatal care consists of four fundamental categories according to the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists 1:

• Physical assessment: Regular monitoring of maternal vital signs, weight, fundal height, and fetal heart tones 2
• Risk screening: Evaluation for biomedical, behavioral, and social risks that could affect pregnancy outcomes 1
• Medical interventions: Laboratory testing, ultrasound examinations, vaccinations, and treatment of identified conditions 3
• Psychosocial interventions: Patient education, counseling on nutrition and lifestyle modifications, and assessment of social support systems 2

Standard Visit Schedule

For uncomplicated, low-risk pregnancies, the American College of Obstetricians and Gynecologists recommends monthly visits until 28 weeks' gestation, biweekly visits from 28-36 weeks, then weekly visits until delivery. 4 This schedule, established in 1930 and maintained through current 2017 guidelines, remains unchanged despite technological advances 1.

The rationale for this timing includes:

• Monthly visits (initial visit through 28 weeks): Monitor maternal health parameters, screen for gestational diabetes, and assess fetal growth 4
• Biweekly visits (28-36 weeks): Increase surveillance as pregnancy advances and complication risks rise 4
• Weekly visits (36 weeks to delivery): Monitor for labor signs, assess fetal well-being, and detect late-developing complications like preeclampsia 4

Critical Timing for Specific Assessments

Certain screening tests must occur at specific gestational ages to be effective:

• First trimester: Dating ultrasound for accurate gestational age determination, which is critical to prevent unnecessary inductions and allow accurate treatment of preterm labor 3
• 12-14 weeks: Early gestational diabetes screening for women with BMI ≥30 kg/m² or prior gestational diabetes 4
• 18-20 weeks: Anatomy ultrasound to evaluate fetal structure and development 4
• 24-28 weeks: Universal gestational diabetes screening for all women not previously diagnosed 4
• 35-37 weeks: Group B streptococcus testing, with intrapartum antibiotic prophylaxis if positive to reduce neonatal infection risk 3

Essential Interventions

By the time pregnant women have their first prenatal visit, it may be too late to prevent some placental development problems or birth defects, as organogenesis begins early in pregnancy and neural tube closure occurs at 28 days after conception. 1 This underscores the importance of preconception care.

Key evidence-based interventions include:

• Folic acid supplementation: Should begin before conception to reduce neural tube defect risk, as supplementation after 6 weeks' gestation (28 days post-conception) has no demonstrated benefit 1
• Rho(D) immune globulin: Markedly decreases alloimmunization risk in RhD-negative women carrying RhD-positive fetuses 3
• Iron deficiency screening and treatment: Reduces risks of preterm labor, intrauterine growth retardation, and perinatal depression 3
• Influenza vaccination: Recommended for all pregnant women 3
• Screening for infections: Asymptomatic bacteriuria and sexually transmitted infections should be tested 3

High-Risk Pregnancy Modifications

For high-risk conditions like preeclampsia or fetal growth restriction, the standard visit schedule is inadequate and requires intensified surveillance. 4

Modified schedules include:

• Preeclampsia: Serial ultrasound evaluations every 2 weeks minimum for fetal growth, amniotic fluid, and umbilical artery Doppler from 24 weeks until birth 4
• Fetal growth restriction: Biweekly ultrasound assessments as the minimum interval once suspected or confirmed 4
• Most high-risk conditions: Weekly or twice-weekly antenatal surveillance becomes standard at 32-34 weeks' gestation, though this frequency lacks rigorous scientific evidence 4

Important Clinical Caveats

Several limitations of prenatal care warrant emphasis:

• No single antenatal test has proven superior for identifying fetuses at risk of intrauterine demise 4
• Antenatal surveillance cannot predict stillbirth from acute events such as placental abruption or cord accidents 4
• Routine antenatal testing does not improve outcomes in low-risk pregnancies and may cause iatrogenic prematurity from false-positive results 4
• Many elements of routine prenatal care are based on tradition and lack a firm evidence base, though some elements are supported by rigorous studies 3

The Broader Context

The goal of regionalized maternal care is for pregnant women at high risk to receive care in facilities prepared to provide the required level of specialized care, thereby reducing maternal morbidity and mortality. 1 This includes a tiered system from birth centers for low-risk women through Level IV regional perinatal health care centers for the highest-risk patients 1.

The United States currently ranks 60th in the world for maternal mortality, with rates worsening over the past 14 years despite prenatal care availability 1. This highlights that prenatal care, while essential, is only one component of a comprehensive perinatal health system that must also address social determinants of health, access barriers, and quality of care delivery 5.