Antepartum care (first trimester): Clinical sciences

First trimester antepartum care refers to pregnancy care prior to 14 weeks of gestation. It’s important for patients to receive early prenatal care to prevent complications and optimize pregnancy outcomes. This is also the optimal time to confirm both viability and gestational age of the pregnancy. During this time, all pregnant patients in the first trimester warrant a complete history and physical exam; screening for high-risk conditions; baseline lab tests; genetic counseling and screening; diet and exercise counseling; and overall education in regard to pregnancy.

When assessing a patient presenting for an initial first trimester antepartum care visit, meaning an initial visit through 13 and 6/7 weeks gestation, your first step is to obtain a focused history and physical exam. History may reveal common first trimester symptoms, such as nausea, vomiting, breast pain, fatigue, cramping, and bleeding. The physical may demonstrate the Hegar sign as early as 6 weeks, which is when the cervix feels softened and enlarged. This is the earliest exam finding of pregnancy. After 12 weeks of gestation, the uterus may appear above the pubic symphysis on a bimanual exam.

Speculum exam may show a Chadwick sign, which is a blue discoloration of the cervix secondary to venous congestion. Keep in mind that patients usually present for this initial visit suspecting pregnancy because of a positive home pregnancy test or missing a menstrual period, but it’s important to confirm the pregnancy with a human chorionic gonadotropin, or hCG, test. If the hCG is negative, consider an alternative diagnosis. However, if the hCG is positive, go ahead and initiate first trimester antepartum care.

Here’s a clinical pearl! If hCG is positive, be sure to note the first day of their last menstrual period, which will provide a clue about the gestational age; and use the Naegale rule by subtracting 3 months and adding 7 days from their last menstrual period, which will give you a preliminary date for their estimated date of delivery.

First, obtain a detailed history to screen for any high-risk conditions. All patients should be screened for depression and anxiety, starting in the first trimester and then periodically through pregnancy and postpartum. This is very important because infants of depressed caregivers can display delayed psychologic, cognitive, neurologic, and motor development. Additionally, patients should be screened for intimate partner violence starting in the first trimester, and continuing periodically to their postpartum checkup.

It’s equally important to identify patients who have chronic hypertension, which puts them at increased risk for preeclampsia. To reduce their risk, start these patients on low-dose aspirin after 12 weeks of gestation. Tight blood pressure control improves pregnancy outcomes in patients with chronic hypertension, so consider starting an antihypertensive for blood pressures greater than 140 over 90.

Also, it’s worth asking about any other medical issues, like a history for past STIs, especially genital HSV; and check their medications so you can transition from potential teratogens as early as possible. For example, patients with a seizure disorder or hypertension could be taking a medication with teratogenic effects.

Make sure to determine if your patient needs an early screen for gestational diabetes, such as those with a body mass index of at least 25; and screen for prior preterm births so you can counsel on second trimester interventions, such as a cerclage or vaginal progesterone. Patients with high-risk conditions will likely need more frequent visits in the first trimester as well as later in the pregnancy.

Next, a complete physical exam should be done at the first antenatal care visit. This establishes a baseline for comparison if any future concerns arise. Assess the head, eyes, ears, nose, and throat, including the thyroid. Auscultate the heart and lungs; and inspect the abdomen, skin, and extremities; and include a musculoskeletal and neurologic exam, especially if your patient has a physical disability. Perform a breast exam, since the breasts undergo substantial changes in pregnancy. A pelvic exam is helpful to look for cervical and vaginal problems, to assess uterine size and presence of any abnormal vulvovaginal lesions or discharge. Address any abnormalities.

Depending on the availability of resources, an ideal time to perform an obstetric ultrasound is in the first trimester, usually between 8 to 12 weeks. This first trimester scan can be used to assess viability, especially if your patient is experiencing symptoms like pelvic cramping or vaginal bleeding, or if they conceived using fertility assistance. You can also check for multiple gestation,