Antepartum care (first trimester): Clinical sciences

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Introduction0:00–0:45

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.

Focused H&P0:45–2:22

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.

Assess for High-Risk Conditions 2:22–4:05

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.

Complete PE4:05–4:50

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.

Obstetric US4:50–6:13

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, and confirm the presence of an intrauterine versus an ectopic pregnancy. Additionally, ultrasound confirmation of the due date could occur either in the first or second trimester up to 22 weeks and 0 days of gestation, but the first trimester is the best and most accurate time.
Here's a clinical pearl! In the first trimester, the due date is determined by comparing the gestational age calculated by the last menstrual period to standardized measurements of the crown rump length.
For pregnancies before 9 weeks, assign a new due date if the gestational age by ultrasound is more than 5 days off from menstrual dates.
If the patient is still in the first trimester but 9 weeks or more gestation, redate the pregnancy if ultrasound measurements are more than 7 days different.
Once a due date is established, it’s important to not change the date, even if an ultrasound later in pregnancy shows a different date.
Next, let’s talk about standard prenatal labs. Order a blood type and antibody screen for everyone.

Prenatal Lab Testing6:13–7:23

Remind any patient who is Rh negative that they’ll need Rh immunoglobulin for any vaginal bleeding during pregnancy, in addition to routine third trimester administration.
Order a CBC to screen for anemia in all patients. Avoid vertical transmission of infectious disease by testing for hepatitis B surface antigen; hepatitis C antibody; syphilis; HIV; gonorrhea; and chlamydia.
It’s also helpful to test for immunity to rubella and varicella by checking immunoglobulin G levels. This tells you if a patient is at risk for infection during the pregnancy and if they require immunization postpartum.
Also screen for urine protein content and culture, and treat abnormal results. Some cultures may show Group B streptococcus, which means they’ll require antibiotics when they go into labor.
Lastly, pregnancy doesn’t alter cervical cancer screening intervals, so don’t forget to obtain a specimen if they are due.
Next up is genetic counseling and screening. This starts with asking about a family history of any genetic diseases, and carrier screening for autosomal recessive conditions, such as cystic fibrosis, spinal muscular atrophy, and hemoglobinopathies.

Genetic Screening and Counseling7:23–8:44

Because carrier status doesn’t change, these tests only should be done if the patient has never had testing before. Be sure to include paternal lineage, if known.
Also, offer diagnostic testing, along with a discussion of associated risks, benefits, and alternatives. In the first trimester, diagnostic testing involves chorionic villus sampling between 10 and 14 weeks.
Screening can be done by using transvaginal ultrasound to measure nuchal translucency; and by checking serum analytes that include free or total beta-hCG; pregnancy-associated plasma protein A, or PAPP-A; and sometimes alpha-fetoprotein, or AFP, depending on lab availability.
Another method of screening for fetal chromosomal abnormalities, called non-invasive prenatal testing, or NIPT, checks for fetal cell-free DNA in the maternal blood.
This test can be done at any time during pregnancy, but is usually performed in the first trimester.Now on to counseling on diet and exercise.

Dietary and Exercise Counseling8:44–9:57

Patients should take a daily prenatal vitamin, ideally a month prior to conceiving, and then throughout the pregnancy to ensure adequate intake of folic acid, iron, and other micronutrients.
Some patients may require additional iron supplementation if iron-deficiency anemia is present. While the focus in pregnancy should be on a balanced diet and exercise that maintains a healthy lifestyle, both insufficient and excess weight gain are risk factors for adverse outcomes.
Therefore, counsel them on ideal weight gain based on their prepregnancy weight; and make sure they know that most exercise is safe in pregnancy, although they should avoid high-impact exercise or anything that can result in abdominal trauma.
It’s important to review dietary restrictions, such as avoiding unpasteurized milk or cheese, as well as luncheon meats, to minimize the risk of acquiring listeriosis.
Warn about consuming fish high in mercury, like marlin and swordfish, as high levels can damage the fetal nervous system.
Limit caffeine to about one cup of coffee per day, and encourage cessation of any tobacco, alcohol, cannabinoid, or illicit substance use.
In addition to everything we’ve already covered, patients should be counseled on general expectations. Let them know to expect visits about every 4 weeks if the first trimester is uncomplicated.

Pregnancy Education9:57–10:20

Review safe over-the-counter medications for common complaints, and inform them of issues that would prompt medical care, such as vaginal bleeding or severe pain.Alright, as a quick recap….
First trimester antepartum care occurs up until the 14th week of pregnancy. While each patient’s care should be tailored based on individual needs, a first trimester ultrasound can be considered in all patients.

Review10:20–10:49

Additionally, for all patients you should perform a complete physical exam; assess for high-risk conditions; obtain routine prenatal lab testing; provide genetic screening and counseling; perform diet and exercise counseling; and review expectations for the pregnancy.