04 Prenatal Care and Pregnancy Health

Purpose and individualized planning

Prenatal care supports the health of the pregnant person and developing fetus through assessment, screening, prevention, education, and timely treatment. Care should begin as soon as pregnancy is suspected. The plan, including visit timing and tests, should be individualized to health history, pregnancy risks, and the patient’s preferences.

Screening looks for increased risk and does not always establish a diagnosis. Explain each test’s purpose and limitations, available follow-up options, and the voluntary nature of prenatal genetic screening and diagnostic testing.

Physiologic changes during pregnancy

Hormonal and circulatory adaptations support fetal growth and prepare the body for birth. These changes can affect examination findings and laboratory values, so results should be interpreted using pregnancy-specific context rather than nonpregnant reference expectations alone.

• Cardiovascular and blood: Blood volume and cardiac output rise, while systemic vascular resistance and blood pressure often fall in early to mid-pregnancy. Plasma volume rises more than red-cell mass, producing mild hemodilution called Physiologic anemia. Pregnancy also increases blood-clotting tendency.

• Respiratory: Increased progesterone-driven ventilation can cause mild breathlessness, especially with exertion. Severe or sudden difficulty breathing is not a routine change.

• Renal and urinary: Increased renal blood flow and filtration can contribute to urinary frequency. Urinary stasis and asymptomatic bacteriuria are clinically important, so early urine culture is commonly included in care.

• Gastrointestinal: Nausea, reflux, constipation, and slower gastrointestinal motility are common. Persistent vomiting or inability to keep fluids down needs prompt assessment.

• Reproductive and skin: The uterus enlarges; breast tenderness and enlargement, increased vaginal discharge, and skin pigmentation changes may occur. Normal discharge should not be confused with fluid leakage, bleeding, or foul-smelling discharge.

Assessment and routine visits

The first visit establishes a baseline and identifies factors that may change the care plan. Review the last menstrual period and prior pregnancy records, then estimate gestational age and due date, using ultrasound when indicated. Take a medical, surgical, family, medication, allergy, and obstetric history.

Ask respectfully and without judgment about mental health, substance use, intimate-partner safety, work or environmental exposures, nutrition, housing, transportation, and support needs. Record baseline vital signs, height and weight, and body mass index; perform a physical examination as appropriate. Explain how to contact the care team and where to seek urgent care. Medicines—including over-the-counter drugs, supplements, and herbal products—should be reviewed with a clinician before use or discontinuation.

Visit frequency and format are tailored to clinical needs. Routine in-person assessments commonly include blood pressure, weight, and symptoms. Once appropriate for gestational age, they may also include fetal heart rate and Fundal height. Review test results, fetal movement when relevant, questions, and new concerns at each visit. Medical conditions, multiple gestation, abnormal findings, or other risk factors may require additional monitoring or specialist consultation.

Screening and testing through pregnancy

Common tests and assessments are timed across pregnancy. Exact timing and test panels can vary with history, local guidance, and the patient’s choices.

• Early pregnancy: Common testing includes a complete blood count, blood type and Rh factor, urine culture, and infection screening, commonly including HIV, syphilis, hepatitis B, and hepatitis C. Chlamydia and gonorrhea testing is based on age, history, and risk. Review immunity and vaccination history.

• From about 10 weeks: Offer counseling about prenatal genetic screening options, including Cell-free DNA screening for common chromosome conditions. A screening result is not a diagnosis; a positive result should prompt counseling and discussion of diagnostic testing.

• 18–22 weeks: Ultrasound is used to assess fetal anatomy. It is recommended even when genetic screening is reassuring.

• 24–28 weeks: Screen for Gestational diabetes. Repeat a blood count or conduct other tests as clinically indicated.

• Third trimester: Reassess relevant infection risks and testing needs. ACOG recommends syphilis screening at the first visit, in the third trimester, and at delivery. Screen for Group B streptococcus at 36–37 weeks; a positive result informs antibiotic prevention during labor.

Prevention and health education

Health guidance should be tailored to the person’s health status, clinical history, and circumstances.

• Nutrition and supplements: Encourage a varied, nutritious diet and a prenatal supplement selected with the care team. CDC recommends 400 micrograms of folic acid daily for people capable of becoming pregnant; some people may receive individualized advice to take a higher dose. Discuss iron and other supplements based on diet, laboratory results, and clinical history. Set weight-gain goals using prepregnancy body mass index and individual circumstances rather than one target for everyone.

• Food safety: Wash produce; avoid unpasteurized dairy and juice, raw or undercooked animal products, and other higher-risk foods. Choose lower-mercury fish and follow current food-safety guidance.

• Activity and daily habits: Regular physical activity is encouraged for most uncomplicated pregnancies, with activity tailored to health status and clinician advice. Avoid alcohol, tobacco, nicotine products, and non-prescribed drugs. Offer supportive help to reduce or stop substance use, and review workplace, household, and environmental exposures.

• Vaccination: Review vaccines during pregnancy with a clinician. Tdap is recommended during every pregnancy, preferably at 27–36 weeks. In most of the continental United States, maternal RSV vaccine is recommended seasonally at 32–36 weeks. Influenza vaccination and other vaccine decisions should follow current guidance and individual circumstances. Live vaccines such as MMR and varicella are generally avoided during pregnancy.

• Preparation and well-being: Discuss childbirth and parenting education, feeding plans, postpartum support, and how to access dental, mental-health, and community services. Encourage patients to share concerns early, including anxiety, depression, or barriers to care.

When to seek urgent care

Teach expectant parents to contact their maternity team promptly about concerning symptoms. Seek immediate medical attention for severe or worsening headache, trouble breathing, severe persistent abdominal pain, heavy bleeding, fluid leaking from the vagina, or a marked decrease or stopping of fetal movement once movement is established.

Severe vomiting with inability to keep fluids down, fainting, or one-sided painful leg swelling also needs urgent assessment. If symptoms feel alarming or something seems seriously wrong, do not wait for the next routine visit.