1 Foundations and Prenatal Care

Principles of prenatal care

Maternal-newborn care supports the health, safety, and informed choices of the pregnant patient and developing fetus from pregnancy confirmation through birth and the newborn period. Prenatal care combines assessment, screening, health education, counseling, and coordination of services. It should be individualized, respectful, and responsive to the patient’s preferences, health needs, and circumstances.

Early care helps establish a baseline and identify needs. Contact a qualified prenatal care provider when pregnancy is suspected, even if the first appointment cannot occur immediately.

Communication and practical support

Person-centered communication includes explaining questions and procedures, protecting privacy, using the patient’s preferred language and name, and supporting informed decisions. Ask about practical needs such as transportation, food access, insurance, and support, because these can affect access to care. Ask sensitive questions about mental health, substance use, relationships, or safety privately and without judgment.

Reproductive and health history

The initial reproductive and health history helps estimate pregnancy duration, identify health concerns, and tailor screening and follow-up. Review the first day of the last menstrual period (LMP), usual cycle length and regularity, previous pregnancies and their outcomes, and any history of ectopic pregnancy, miscarriage, stillbirth, preterm birth, cesarean birth, preeclampsia, or gestational diabetes.

Also review chronic conditions, prior operations, allergies, and current or recent prescription and nonprescription medicines, vitamins, and supplements. Ask about relevant health conditions, inherited disorders, and birth defects in the patient’s family and, when relevant, the other biological parent’s family.

The history also includes pregnancy intentions and concerns, tobacco, alcohol and other substance use, work or environmental exposures, emotional well-being, support, and safety. Ask sensitive questions confidentially and explain how the information will be used.

Summarizing pregnancy outcomes

Obstetric shorthand may be used to summarize outcomes. G is the total number of pregnancies, including the current one; T is the number of term births; P is the number of preterm births; A is the number of pregnancies ending before the locally defined threshold of viability, including spontaneous or induced losses; and L is the number of living children.

For example, G3 T1 P1 A0 L2 means three pregnancies including the current pregnancy, one term birth, one preterm birth, no earlier pregnancy losses, and two living children. Conventions can vary, so clarify details rather than relying on the code alone.

Pregnancy confirmation

Pregnancy tests detect human chorionic gonadotropin (hCG), a hormone produced after implantation. Home and point-of-care urine tests are commonly used. Blood tests can detect smaller amounts of hCG and may be used when clinically indicated.

A positive test establishes that hCG is present, but does not by itself determine pregnancy location, viability, or gestational age. Ultrasound or quantitative blood hCG may be considered when symptoms, dates, or clinical findings call for further evaluation.

Pregnancy dating

Pregnancy is conventionally dated in gestational weeks, counted from the first day of the LMP rather than from conception. If cycles are regular and the LMP is known, Naegele’s rule can provide an initial estimated due date (EDD): add 7 days to the first day of the LMP, subtract 3 months, and add 1 year. For example, an LMP of March 10 gives an estimated date of December 17. The result is an estimate, not a prediction of the exact birth date.

An early ultrasound can confirm or refine dating. First-trimester ultrasound is the most accurate ultrasound method for establishing or confirming gestational age. The clinician considers the LMP and the earliest reliable ultrasound, documents the best obstetric estimate and EDD, and generally avoids changing an established date based only on later scans.

A pregnancy without an ultrasound confirming or revising dating before 22 weeks is considered a suboptimally dated pregnancy.

The first prenatal visit

The first prenatal visit is usually more comprehensive than follow-up visits. It commonly includes reviewing history and medications, assessing general health and pregnancy-related concerns, confirming dating, and planning ongoing care. Depending on the patient’s needs and prior records, the examination may include vital signs and a physical or pelvic examination.

The provider discusses appropriate screening and diagnostic options, answers questions, and identifies potentially helpful referrals or supports. Early-pregnancy testing commonly includes a complete blood count, blood type and Rh factor, and urine testing or culture. Screening for infections such as HIV, syphilis, hepatitis B and C, and other infections when indicated is also part of routine care. The exact tests depend on current guidance, individual risk, and prior results. Patients should be told what each test is for and how results may affect care.

Ongoing prenatal visits

Prenatal care continues through scheduled visits, with timing and format tailored to clinical needs and available services. A fixed schedule of monthly visits followed by more frequent visits is not a universal requirement. Visit frequency can vary with pregnancy risk, patient preferences, local practice, and whether particular assessments need to occur in person. Higher-risk conditions or new concerns may require closer follow-up or specialist care.

At follow-up visits, the care team reviews new symptoms and concerns, checks blood pressure and weight as appropriate, and assesses pregnancy progress. As pregnancy advances, assessments may include uterine fundal height and fetal heart rate. Tests and counseling are scheduled at appropriate stages, including screening for gestational diabetes and discussion of genetic screening or ultrasound options. Patients should have opportunities to ask questions and participate in decisions.