A 24-year-old woman visits her physician to seek preconception advice. She is recently married and plans to have a child soon. Menses occur at regular 28-day intervals and last 5 days. She has sexual intercourse only with her husband and, at this time, they consistently use condoms for birth control. The patient consumes a well-balanced diet with moderate intake of meat and dairy products. She has no history of serious illness and takes no medications currently. She does not smoke or drink alcohol. The patient’s history reveals no birth defects or severe genetic abnormalities in the family. Physical examination shows no abnormalities. Pelvic examination indicates a normal vagina, cervix, uterus, and adnexa. To decrease the likelihood of fetal neural-tube defects in her future pregnancy, which of the following is the most appropriate recommendation for initiation of folic acid supplementation?

As soon as her pregnancy is confirmed

No folic acid supplement is required as nutritional sources are adequate

In the second half of pregnancy

A 28-year-old female in the 2nd trimester of pregnancy is diagnosed with primary Toxoplasma gondii infection. Her physician fears that the fetus may be infected in utero. Which of the following are associated with T. gondii infection in neonates?

Hydrocephalus, chorioretinitis, intracranial calcifications

Hutchinson’s teeth, saddle nose, short maxilla

Deafness, seizures, petechial rash

Patent ductus arteriosus, cataracts, deafness

Temporal encephalitis, vesicular lesions

A 23-year-old nulligravida presents for evaluation 5 weeks after her last menstrual period. Her previous menstruation cycle was regular, and her medical history is benign. She is sexually active with one partner and does not use contraception. A urine dipstick pregnancy test is negative. The vital signs are as follows: blood pressure 120/80 mm Hg, heart rate 71/min, respiratory rate 13/min, and temperature 36.8°C (98.2°F). The physical examination is notable for breast engorgement, increased pigmentation of the nipples, and linea nigra. The gynecologic examination demonstrates cervical and vaginal cyanosis. Measurement of which of the following substances is most appropriate in this case?

Blood human chorionic gonadotropin

Urinary human chorionic gonadotropin

A 29-year-old woman presents to a medical office complaining of fatigue, nausea, and vomiting for 1 week. Recently, the smell of certain foods makes her nauseous. Her symptoms are more pronounced in the mornings. The emesis is clear-to-yellow without blood. She has had no recent travel out of the country. The medical history is significant for peptic ulcer, for which she takes pantoprazole. The blood pressure is 100/60 mm Hg, the pulse is 70/min, and the respiratory rate is 12/min. The physical examination reveals pale mucosa and conjunctiva, and bilateral breast tenderness. The LMP was 9 weeks ago. What is the most appropriate next step in the management of this patient?

Beta-HCG levels and a transvaginal ultrasound

Beta-HCG levels and a transabdominal ultrasound

Beta-HCG levels and a pelvic CT

A 26-year-old woman presents to the women’s health clinic with a 9-week delay in menses. The patient has a history of grand mal seizures, and was recently diagnosed with acute sinusitis. She is prescribed lamotrigine and amoxicillin. The patient smokes one-half pack of cigarettes every day for 10 years, and drinks socially a few weekends every month. Her mother died of breast cancer when she was 61 years old. The vital signs are stable during the current office visit. Physical examination is grossly normal. The physician orders a urine beta-hCG that comes back positive. Abdominal ultrasound shows an embryo consistent in dates with the first day of last menstrual period. Given the history of the patient, which of the following would most likely decrease congenital malformations in the newborn?

Switching to another antiepileptic medication

Nutrition in pregnancy for USMLE Step 1: High-Yield OB/GYN Lessons

Weight & Calories - Fueling for Two

IOM Recommended Total Weight Gain (by pre-pregnancy BMI):
- Underweight (<18.5): 28-40 lbs (12.5-18 kg)
- Normal weight (18.5-24.9): 25-35 lbs (11.5-16 kg)
- Overweight (25.0-29.9): 15-25 lbs (7-11.5 kg)
- Obese (≥30.0): 11-20 lbs (5-9 kg)
Caloric Intake Increase:
- 1st Trimester: No change
- 2nd Trimester: ↑ ~340 kcal/day
- 3rd Trimester: ↑ ~450 kcal/day

⭐ Excessive gestational weight gain is a major risk factor for fetal macrosomia (>4-4.5 kg), leading to birth complications, and increases the mother's risk for postpartum weight retention and future obesity.

Macronutrients - The Big Three

Carbohydrates: Primary energy source for mother and fetus. Prioritize complex carbs (whole grains, vegetables) over simple sugars to maintain stable blood glucose.
Protein: Foundational for fetal tissue, brain, and organ development. Supports expansion of maternal tissues (uterus, blood volume).
- Intake should increase to ~1.1 g/kg/day.
Fats: Crucial for fetal neurodevelopment and fat-soluble vitamin absorption.
- Emphasize unsaturated fats and omega-3 fatty acids (DHA, EPA) from sources like low-mercury fish.

Healthy Plate: Vegetables, Protein, Carbs

⭐ Maternal protein deprivation can lead to intrauterine growth restriction (IUGR) and smaller head circumference.

Micronutrients - Vital Little Helpers

Folic Acid (Vitamin B9): Crucial for neural tube development.
- Standard risk: 0.4-0.8 mg/day, starting pre-conception.
- High risk (e.g., prior NTD, anti-epileptic drugs): 4 mg/day.
Iron: Prevents maternal anemia and supports fetal red blood cell production.
- Supplement with 27 mg/day of elemental iron.
- Screen for anemia at initial visit and 24-28 weeks.
Calcium: Essential for fetal bone and teeth formation.
- Recommended intake: 1,000-1,300 mg/day.
Vitamin D: Aids calcium absorption.
- Recommended intake: 600 IU/day.
Iodine: Critical for fetal brain development.

⭐ To be most effective at preventing neural tube defects, folic acid supplementation should begin at least 1 month before conception.

Food Safety - Danger Zone Delicacies

General Principle: Avoid unpasteurized, raw, or undercooked foods. Thoroughly wash all produce.
Specific Pathogens & Toxins:
- Listeria monocytogenes:
  - Sources: Unpasteurized dairy (soft cheeses like feta, Brie), deli meats, pâté, hot dogs.
  - Risk: Can cross placenta → neonatal sepsis, preterm labor, stillbirth.
  - Prevention: Cook deli meats until steaming hot; choose hard cheeses.
- Toxoplasma gondii:
  - Sources: Raw/undercooked meat, unwashed vegetables, cat feces (oocysts).
  - Risk: Congenital toxoplasmosis.
- Methylmercury:
  - Sources: Large predatory fish (shark, swordfish, king mackerel, tilefish).
  - Risk: Fetal neurotoxicity.
  - Safe options: Salmon, shrimp, tilapia (limit to <12 oz/week).

⭐ Classic Triad of Congenital Toxoplasmosis: chorioretinitis, hydrocephalus, and intracranial calcifications.

Foods to Eat and Avoid During Pregnancy

High‑Yield Points - ⚡ Biggest Takeaways

Folic acid supplementation is critical to prevent neural tube defects; use higher doses for high-risk patients (e.g., prior NTD, anti-seizure meds).

Increased iron demand (to 27 mg/day) supports maternal hemoglobin synthesis and fetal growth; screen for anemia.

Adequate calcium (1000-1300 mg/day) and Vitamin D are essential for fetal skeletal mineralization.

Avoid unpasteurized dairy/deli meats (Listeria), high-mercury fish, and undercooked meat (Toxoplasma).

Appropriate weight gain depends on pre-pregnancy BMI.

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