A 24-year-old primigravida presents to her physician for regular prenatal care at 31 weeks gestation. She has no complaints and the antepartum course has been uncomplicated. Her pre-gestational history is significant for obesity (BMI = 30.5 kg/m2). She has gained a total of 10 kg (22.4 lb) during pregnancy, and 2 kg (4.48 lb) since her last visit 4 weeks ago. Her vital signs are as follows: blood pressure, 145/90 mm Hg; heart rate, 87/min; respiratory rate, 14/min; and temperature, 36.7℃ (98℉). The fetal heart rate is 153/min. The physical examination shows no edema and is only significant for a 2/6 systolic murmur best heard at the apex of the heart. A 24-hour urine is negative for protein. Which of the following options describe the best management strategy in this case?

Observation in the outpatient settings

Treatment in outpatient settings with labetalol

Treatment in the outpatient settings with nifedipine

Treatment in the inpatient settings with methyldopa

Admission to hospital for observation

A 29-year-old G2P2 female gives birth to a healthy baby boy at 39 weeks of gestation via vaginal delivery. Immediately after the delivery of the placenta, she experiences profuse vaginal hemorrhage. Her prior birthing history is notable for an emergency cesarean section during her first pregnancy. She did not receive any prenatal care during either pregnancy. Her past medical history is notable for obesity and diabetes mellitus, which is well controlled on metformin. Her temperature is 99.0°F (37.2°C), blood pressure is 95/50 mmHg, pulse is 125/min, and respirations are 22/min. On physical examination, the patient is in moderate distress. Her extremities are pale, cool, and clammy. Capillary refill is delayed. Which of the following is the most likely cause of this patient’s bleeding?

Chorionic villi attaching to the myometrium

Chorionic villi invading into the myometrium

Placental implantation over internal cervical os

Chorionic villi attaching to the decidua basalis

Chorionic villi invading into the serosa

A 24-year-old woman comes to the physician for preconceptional advice. She has been married for 2 years and would like to conceive within the next year. Menses occur at regular 30-day intervals and last 4 days with normal flow. She does not smoke or drink alcohol and follows a balanced diet. She takes no medications. She is 160 cm (5 ft 3 in) tall and weighs 55 kg (121 lb); BMI is 21.5 kg/m2. Physical examination, including pelvic examination, shows no abnormalities. She has adequate knowledge of the fertile days of her menstrual cycle. Which of the following is most appropriate recommendation for this patient at this time?

Begin high-dose vitamin A supplementation

Begin vitamin B12 supplementation

A 30-year-old woman, gravida 2, para 1, at 42 weeks' gestation is admitted to the hospital in active labor. Pregnancy has been complicated by gestational diabetes, for which she has been receiving insulin injections. Her first child was delivered by lower segment transverse cesarean section because of a nonreassuring fetal heart rate. Her pulse is 90/min, respirations are 18/min, and blood pressure is 135/80 mm Hg. The fetal heart rate tracing shows a baseline heart rate of 145/min and moderate variation with frequent accelerations and occasional early decelerations. She undergoes an elective repeat lower segment transverse cesarean section with complete removal of the placenta. Shortly after the operation, she starts having heavy uterine bleeding with passage of clots. Examination shows a soft uterus on palpation. Her bleeding continues despite fundal massage and the use of packing, oxytocin, misoprostol, and carboprost. Her pulse rate is now 120/min, respirations are 20/min, and blood pressure is 90/70 mm Hg. Her hemoglobin is 8 g/dL, hematocrit is 24%, platelet count is 120,000 mm3, prothrombin time is 11 seconds, and partial thromboplastin time is 30 seconds. Mass transfusion protocol is activated and a B-Lynch uterine compression suture is placed to control her bleeding. Which of the following is the mostly likely cause of her postpartum complication?

Lack of uterine muscle contraction

Adherent placenta to myometrium

Infection of the endometrial lining of the uterus

A 32-year-old G2P0A1 woman presents at 36 weeks of gestation for the first time during her pregnancy. The patient has no complaints, currently. However, her past medical history reveals seizure disorder, which is under control with valproic acid and lithium. She has not seen her neurologist during the past 2 years, in the absence of any complaints. She also reports a previous history of elective abortion. The physical examination is insignificant. Her blood pressure is 130/75 mm Hg and pulse is 80/min. The patient is scheduled to undergo regular laboratory tests and abdominal ultrasound. Given her past medical history, which of the following conditions is her fetus most likely going to develop?

Intrauterine growth restriction

A 26-year-old primigravid woman at 25 weeks' gestation comes to the physician for a prenatal visit. She has no history of serious illness and her only medication is a daily prenatal vitamin. A 1-hour 50-g glucose challenge shows a glucose concentration of 167 mg/dL (N < 135). A 100-g oral glucose tolerance test shows glucose concentrations of 213 mg/dL (N < 180) and 165 mg/dL (N < 140) at 1 and 3 hours, respectively. If she does not receive adequate treatment for her condition, which of the following complications is her infant at greatest risk of developing?

Decreased amniotic fluid production

A 58-year-old woman presents to the physician’s office with vaginal bleeding. The bleeding started as a spotting and has increased and has become persistent over the last month. The patient is G3P1 with a history of polycystic ovary syndrome and type 2 diabetes mellitus. She completed menopause 4 years ago. She took cyclic estrogen-progesterone replacement therapy for 1 year at the beginning of menopause. Her weight is 89 kg (196 lb), height 157 cm (5 ft 2 in). Her vital signs are as follows: blood pressure 135/70 mm Hg, heart rate 78/min, respiratory rate 12/min, and temperature 36.7℃ (98.1℉). Physical examination is unremarkable. Transvaginal ultrasound reveals an endometrium of 6 mm thickness. Speculum examination shows a cervix without focal lesions with bloody discharge from the non-dilated external os. On pelvic examination, the uterus is slightly enlarged, movable, and non-tender. Adnexa is non-palpable. What is the next appropriate step in the management of this patient?

Hysteroscopy with targeted biopsy

Hysteroscopy with dilation and curettage

Medroxyprogesterone acetate therapy

Obesity in pregnancy for USMLE Step 3: High-Yield OB/GYN Lessons

Risks & Complications - The Heavy Burden

Maternal Risks:
- ↑ Gestational Diabetes (GDM) & insulin resistance.
- ↑ Hypertensive disorders (preeclampsia, chronic HTN).
- ↑ Venous thromboembolism (VTE).
- ↑ Cesarean delivery rates & associated morbidity (e.g., infection, blood loss).
- Failed induction, dysfunctional labor.
Fetal & Neonatal Risks:
- Macrosomia (birth weight > 4000-4500 g) → shoulder dystocia.
- ↑ Congenital anomalies (neural tube defects, cardiac).
- ↑ Stillbirth / Intrauterine Fetal Demise (IUFD).
- Neonatal hypoglycemia.
- Childhood obesity.

⭐ Maternal obesity is an independent risk factor for neural tube defects, warranting higher dose folic acid supplementation pre-conceptionally and in early pregnancy.

Antenatal Management - Proactive Pregnancy Patrol

Weight & Lifestyle Counseling:
- Establish strict weight gain goals based on IOM:
  - Overweight (BMI 25-29.9): 15-25 lb
  - Obese (BMI ≥30): 11-20 lb
- Refer for nutritional counseling.
- Advise moderate-intensity exercise, ~150 min/week.
Screening & Prophylaxis:
- Early glucose challenge test or HbA1c for pre-existing diabetes.
- Low-dose aspirin (81 mg/day) initiated between 12-16 weeks for preeclampsia prophylaxis.
- Standard GDM screening with 1-hr GCT at 24-28 weeks.
Fetal Surveillance:
- Detailed anatomy scan (18-22 weeks); visualization may be limited.
- Consider serial growth scans in the 3rd trimester for macrosomia/FGR.

⭐ For patients with obesity (a significant risk factor for preeclampsia), initiating low-dose aspirin before 16 weeks is a key evidence-based intervention to mitigate risk.

Intrapartum & Postpartum - The Final Stretch

Intrapartum Management:
- Labor: Higher risk of dystocia (prolonged labor) and failed induction.
- Delivery: Increased rates of operative vaginal delivery and cesarean section.
- Anesthesia: Anticipate difficult epidural/spinal placement. Higher failure rate of regional anesthesia, potentially requiring general anesthesia. Anesthesia consult is recommended.
Postpartum Risks:
- Hemorrhage: ↑ risk of postpartum hemorrhage (PPH) from uterine atony.
- VTE: Significantly elevated risk for venous thromboembolism. Utilize mechanical and/or pharmacologic prophylaxis.
- Wound: ↑ risk of C-section wound infection, seroma, and dehiscence.

Obstetric Complications by Maternal BMI

⭐ Women with a BMI >30 have a 2-3 fold increased risk of requiring a cesarean delivery and a significantly higher risk of postpartum venous thromboembolism.

Weight & Counseling - Pounds and Plans

IOM Gestational Weight Gain (GWG) Recommendations:
- Underweight (BMI < 18.5): Gain 28-40 lbs
- Normal weight (BMI 18.5-24.9): Gain 25-35 lbs
- Overweight (BMI 25.0-29.9): Gain 15-25 lbs
- Obese (BMI ≥ 30.0): Gain 11-20 lbs
Counseling Focus:
- Diet: Refer to a nutritionist. Emphasize balanced meals, avoiding empty calories. Caloric restriction for weight loss is contraindicated.
- Exercise: Advise 30+ minutes of moderate activity (e.g., walking, swimming) on most days of the week, if not contraindicated.

⭐ Exam Favorite: Excessive gestational weight gain, especially in obese women, significantly ↑ the risk of fetal macrosomia ($> 4000-4500$ g), cesarean delivery, and long-term maternal/child obesity.

Pre-conception counseling on weight loss and nutritional optimization is the most critical intervention.

Major maternal risks include gestational diabetes, preeclampsia, VTE, and higher C-section rates.

Key fetal risks are macrosomia, neural tube defects (NTDs), stillbirth, and future childhood obesity.

Mandates early glucose screening for GDM and a higher dose of folic acid to reduce NTD risk.

Labor may be complicated by failed induction, prolonged stages, and anesthesia challenges.

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