Well-coordinated prenatal care that follows an evidence-based, informed process results in fewer hospital admissions, improved education, greater satisfaction, and lower pregnancy-associated morbidity and mortality. Care initiated at 10 weeks or earlier improves outcomes. Identification and treatment of periodontal disease decreases preterm delivery risk. A prepregnancy body mass index greater than 25 kg per m² is associated with gestational diabetes mellitus, hypertension, miscarriage, and stillbirth. Advanced maternal and paternal age (35 years or older) is associated with gestational diabetes, hypertension, miscarriage, intrauterine growth restriction, aneuploidy, birth defects, and stillbirth. Rh_o(D) immune globulin decreases alloimmunization risk in a patient who is RhD-negative carrying a fetus who is RhD-positive. Treatment of iron deficiency anemia decreases the risk of preterm delivery, intrauterine growth restriction, and perinatal depression. Ancestry-based genetic risk stratification using family history can inform genetic screening. Folic acid supplementation (400 to 800 mcg daily) decreases the risk of neural tube defects. All pregnant patients should be screened for asymptomatic bacteriuria, sexually transmitted infections, and immunity against rubella and varicella and should receive tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap), influenza, and COVID-19 vaccines. Testing for group B Streptococcus should be performed between 36 and 37 weeks, and intrapartum antibiotic prophylaxis should be initiated to decrease the risk of neonatal infection. Because of the impact of social determinants of health on outcomes, universal screening for depression, anxiety, intimate partner violence, substance use, and food insecurity is recommended early in pregnancy. Screening for gestational diabetes between 24 and 28 weeks is recommended for all patients. People at risk of preeclampsia, including those diagnosed with COVID-19 in pregnancy, should be offered 81 mg of aspirin daily starting at 12 weeks. Chronic hypertension should be treated to a blood pressure of less than 140/90 mm Hg.