What are the key components of first trimester prenatal care?

First Trimester Prenatal Care Overview

First trimester prenatal care should begin ideally at 10 weeks or earlier, as early initiation is associated with improved maternal and fetal outcomes, fewer hospital admissions, and lower pregnancy-associated morbidity and mortality. 1, 2

Initial Visit Components

History and Risk Assessment

• Comprehensive medical history including reproductive history, previous pregnancy complications (infant death, fetal loss, birth defects, low birth weight, preterm birth), chronic medical conditions, and current medications 3, 1

• Reproductive life planning to understand the patient's intentions regarding pregnancy timing and help develop a plan based on her values and resources 4

• Genetic risk assessment based on maternal age (≥35 years increases chromosomal anomaly risk), ethnic background, family history of genetic disorders, and consanguinity 3, 2

• Medication review with special attention to potentially teratogenic drugs including ACE inhibitors, angiotensin receptor blockers, statins, isotretinoin, warfarin, and certain antiseizure medications 4

• Environmental and occupational exposure assessment for toxins including heavy metals, solvents, pesticides, endocrine disruptors, and allergens at home and workplace 3

• Psychosocial screening for depression, anxiety, intimate partner violence, substance use, and food insecurity 3, 2

Physical Examination

Focused physical examination should emphasize periodontal, thyroid, heart, breast, and pelvic examinations 3, 1

Laboratory Testing

Initial laboratory panel includes: 3, 1, 2

• Complete blood count (to screen for anemia)
• Urinalysis
• Blood type and Rh screen
• Rubella immunity status
• Syphilis screening
• Hepatitis B surface antigen
• HIV testing
• Gonorrhea and chlamydia screening
• Screening for asymptomatic bacteriuria

Additional testing for high-risk patients: 4

• Hemoglobin A1C for women with diabetes
• Creatinine and urinary albumin-to-creatinine ratio for women with diabetes or renal disease
• Thyroid function tests if indicated

Nutritional Interventions

Folic Acid Supplementation

Folic acid 400-800 mcg daily should be initiated immediately (ideally starting at least 1-3 months before conception) to reduce neural tube defect risk by nearly 75%, as neural tube closure occurs at 6 weeks gestation (28 days after conception) 3, 5, 2, 6

Prenatal Vitamins

Prescribe prenatal vitamins containing 400-800 mcg folic acid and 150 mcg potassium iodide to continue throughout pregnancy 1

Nutritional Counseling

• Promote healthy prepregnancy weight with ideal BMI of 19.8-26.0 kg/m² through exercise and nutrition, as BMI >25 kg/m² is associated with gestational diabetes, hypertension, miscarriage, and stillbirth 4, 2

• Encourage "five-a-day" consumption: two servings of fruit and three servings of vegetables daily 4, 1

• Comprehensive nutrition assessment addressing overweight/obesity or underweight status, meal planning, correction of dietary deficiencies, caffeine intake, and safe food preparation techniques 4

Immunizations

Update immunizations as needed: 4, 3, 1

• Influenza vaccine (recommended for all pregnant women)
• Tdap vaccine (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis)
• Hepatitis B (if not immune)
• Rubella (if not immune, must be given before pregnancy)
• Varicella (if not immune, must be given before pregnancy)
• COVID-19 vaccine 2

Critical caveat: Live vaccines (rubella, varicella) must be administered before pregnancy, not during pregnancy 4

Lifestyle Modifications

Substance Avoidance

Counsel complete abstinence from: 4, 1

• Alcohol
• Tobacco (use five A's approach: Ask, Advise, Assess, Assist, Arrange for smoking cessation)
• Recreational drugs
• Teratogenic medications

Healthy Behaviors

Promote: 4, 1

• Regular moderate exercise appropriate for pregnancy
• Adequate sleep
• Avoidance of hyperthermia (hot tubs)
• Seatbelt use
• Safe sex practices
• Adequate hydration

Discourage: 4

• Douching

Infection Prevention Counseling

Provide counseling on preventing TORCH infections (Toxoplasmosis, Other viruses, Rubella, Cytomegalovirus, Herpes simplex) through proper food handling, avoiding cat litter, and hand hygiene 3, 6

Special Considerations for High-Risk Conditions

Diabetes Management

For women with preexisting diabetes: 4, 1

• Target A1C <6.5% before and during pregnancy to minimize risk of congenital anomalies (anencephaly, microcephaly, congenital heart disease, renal anomalies, caudal regression), preeclampsia, and preterm birth
• Establish multidisciplinary care team including endocrinologist, maternal-fetal medicine specialist, registered dietitian, and diabetes educator
• Initiate fasting and postprandial glucose monitoring with targets: fasting <95 mg/dL, 1-hour postprandial <140 mg/dL, or 2-hour postprandial <120 mg/dL
• Dilated eye examination before pregnancy or in first trimester for retinopathy screening

Hypertension Management

Review and adjust antihypertensive medications to avoid ACE inhibitors and angiotensin receptor blockers, which are teratogenic 4, 2

Thyroid Disease

Ensure appropriate medication adjustments for thyroid conditions, as both hypothyroidism and hyperthyroidism can affect pregnancy outcomes 4, 3

Preeclampsia Risk Assessment and Prevention

For women at high risk of preeclampsia (including those with chronic hypertension, diabetes, renal disease, autoimmune disease, or previous preeclampsia): 1, 2, 7

• Initiate low-dose aspirin 81-150 mg daily starting at 12-16 weeks gestation to reduce preeclampsia risk
• Consider calcium supplementation if dietary calcium intake is low 8

Genetic Screening and Counseling

Offer genetic screening based on: 3, 2

• Maternal age ≥35 years
• Ethnic background (e.g., cystic fibrosis carrier screening for Caucasians, sickle cell for African Americans, Tay-Sachs for Ashkenazi Jews)
• Family history of genetic disorders
• Consanguinity

Testing for aneuploidy and neural tube defects should be offered to all pregnant women with discussion of risks and benefits 8

Pregnancy Dating

Establish accurate estimated due date using first-trimester ultrasound (ideally between 8-13 weeks), as correct dating is critical to prevent unnecessary inductions and allow for accurate treatment of preterm labor 8, 7

Rh Status Management

For RhD-negative women: 8, 2

• Confirm Rh status at initial visit
• Plan for Rho(D) immune globulin administration to markedly decrease alloimmunization risk if carrying an RhD-positive fetus

Common Pitfalls to Avoid

• Delaying folic acid supplementation until after the first prenatal visit, when neural tube closure has already occurred at 6 weeks gestation 4

• Failing to screen for and treat periodontal disease, which decreases preterm delivery risk 2

• Not identifying and discontinuing teratogenic medications before organogenesis (5-8 weeks gestation) 4

• Inadequate preconception counseling for women with chronic conditions such as diabetes, where poor glycemic control during early pregnancy significantly increases congenital anomaly risk 4, 1

• Missing opportunities to restore allostasis (stress and inflammatory response regulation) before pregnancy, as chronic stress can increase susceptibility to pregnancy complications including preterm birth 4

Follow-Up Planning

Schedule appropriate referrals: 3

• Maternal-fetal medicine specialists for high-risk conditions
• Genetic counseling when indicated by age, ethnic background, or family history
• Subspecialists as needed for chronic medical conditions

Establish ongoing risk assessment plan, as this should be a continuous process throughout pregnancy 3