Introduction
Pregnancy encompasses approximately 40 weeks (280 days) from the first day of the last menstrual period (LMP) through childbirth. It is divided into three trimesters. Prenatal care involves regular medical visits, screening tests, and education to optimize maternal and fetal outcomes.
Prenatal Care Schedule
Routine Visit Schedule
| Timing | Interval | Key Assessments |
|---|---|---|
| 1st visit before 10 weeks | Initial | Confirm pregnancy, dating ultrasound, medical history, physical exam, labs, discuss screening options |
| 6-8 weeks | Confirm viability | Ultrasound if indicated |
| 8-12 weeks | First prenatal visit | Complete history and physical, initial labs, dating US |
| 11-14 weeks | Nuchal translucency | Combined first-trimester screening (NT + blood) |
| 16-20 weeks | Second trimester | Quad screen or NIPT, anatomy ultrasound (18-22 weeks) |
| 16-28 weeks | Every 4 weeks | Fundal height measurement, fetal heart tones, review symptoms |
| 24-28 weeks | Glucose screening | 1-hour glucose tolerance test for gestational diabetes |
| 28-36 weeks | Every 2 weeks | GBS screening (36-37 weeks), Rhogam (28 weeks if Rh-negative) |
| 36-40 weeks | Weekly | Cervical exam, presentation, fetal position, discuss birth plan |
| 40-41 weeks | Twice weekly | Post-dates assessment, BPP, NST, discuss induction |
| 41+ weeks | Induction recommended | Induction of labor by 41-42 weeks |
Initial Prenatal Labs
| Test | Purpose |
|---|---|
| CBC | Anemia, platelet count |
| Blood type and Rh | Rh incompatibility |
| Antibody screen | Unexpected antibodies |
| Rubella IgG | Immunity status |
| Syphilis (RPR/VDRL) | Screen for syphilis |
| Hepatitis B surface antigen | HBV carrier status |
| HIV (opt-out) | HIV screening |
| Urinalysis and culture | UTI, proteinuria, glucosuria |
| Pap smear (if due) | Cervical cancer screening |
| Chlamydia/gonorrhea (age <25 or risk) | STI screening |
| Varicella IgG | If no history of chickenpox |
| Tuberculosis screening | If high risk |
| Vitamin D | If at risk |
| TSH | Thyroid function (optional; recommended if symptoms or risk) |
Nutrition in Pregnancy
Caloric and Nutrient Requirements
| Nutrient | Daily Requirement | Sources | Importance |
|---|---|---|---|
| Calories | 1st tri: +0; 2nd tri: +340; 3rd tri: +450 | Additional healthy intake | Fetal growth and maternal metabolism |
| Protein | 71 g (vs 46 g non-pregnant) | Lean meat, poultry, fish, eggs, beans, dairy | Tissue growth, fetal development |
| Folate/folic acid | 600-800 mcg | Leafy greens, fortified grains, supplement | Neural tube defect prevention |
| Iron | 27 mg (vs 18 mg) | Red meat, spinach, fortified grains, supplement | Red blood cell expansion, prevent anemia |
| Calcium | 1,000 mg | Dairy, fortified plant milk, leafy greens | Fetal skeletal development, prevent maternal bone loss |
| Vitamin D | 600 IU | Sunlight, fortified milk, supplement | Calcium absorption, immune function |
| DHA (omega-3) | 200-300 mg | Fatty fish (salmon, sardines), supplement | Fetal brain and eye development |
| Iodine | 220 mcg | Iodized salt, seafood, prenatal vitamin | Fetal thyroid and brain development |
| Choline | 450 mg | Eggs, meat, beans, cruciferous vegetables | Neural tube development, brain function |
| Vitamin B12 | 2.6 mcg | Animal products (vegan/vegetarian: supplement) | Neural tube development, red blood cells |
Foods to Avoid
| Food | Risk |
|---|---|
| Raw or undercooked meat, poultry, eggs | Toxoplasmosis, salmonella |
| Unpasteurized dairy products | Listeriosis |
| Certain fish high in mercury (shark, swordfish, king mackerel, tilefish) | Mercury neurotoxicity |
| Deli meats (unless heated to steaming) | Listeriosis |
| Raw sprouts (alfalfa, clover) | Salmonella, E. coli |
| Unwashed produce | Toxoplasmosis, bacteria |
| Alcohol (none in pregnancy) | Fetal alcohol spectrum disorders |
| Caffeine (limit <200 mg/day) | Possible association with miscarriage at high doses |
Weight Gain Recommendations
| Pre-Pregnancy BMI | Total Weight Gain | Weekly Gain (2nd and 3rd Trimester) |
|---|---|---|
| Underweight (<18.5) | 28-40 lb (12.5-18 kg) | 1.0-1.3 lb/week |
| Normal (18.5-24.9) | 25-35 lb (11.5-16 kg) | 0.8-1.0 lb/week |
| Overweight (25-29.9) | 15-25 lb (7-11.5 kg) | 0.5-0.7 lb/week |
| Obese (>30) | 11-20 lb (5-9 kg) | 0.4-0.6 lb/week |
Exercise in Pregnancy
| Exercise Type | Recommendation | Modifications |
|---|---|---|
| Aerobic (walking, swimming, stationary cycling, low-impact aerobics) | 150 minutes/week moderate intensity | Avoid supine position after 20 weeks; stay hydrated; avoid overheating |
| Strength training | Moderate resistance, 2-3x/week | Avoid Valsalva maneuver (bearing down); lighter weights |
| Yoga/Pilates | Modified poses | Avoid deep twists, inversions, hot yoga (Bikram), lying flat on back |
| Running | Continue if pre-pregnancy routine | Decrease intensity; avoid overexertion; maintain hydration |
| Pelvic floor (Kegel) exercises | Daily | Strengthen pelvic floor for labor and postpartum |
Exercise Contraindications
| Absolute | Relative |
|---|---|
| Hemodynamically significant heart disease | Severe anemia |
| Restrictive lung disease | Unevaluated maternal cardiac arrhythmia |
| Incompetent cervix/cerclage | Chronic bronchitis |
| Multiple gestation at risk for preterm labor | Poorly controlled type 1 diabetes |
| Persistent 2nd/3rd trimester bleeding | Extreme morbid obesity |
| Placenta previa after 26 weeks | Extreme underweight (BMI <12) |
| Premature labor during current pregnancy | History of extremely sedentary lifestyle |
| Preeclampsia/pregnancy-induced hypertension | Intrauterine growth restriction (IUGR) |
| Ruptured membranes | Poorly controlled hypertension |
| Preterm labor | Orthopedic limitations |
Common Pregnancy Complaints
| Complaint | Onset | Management |
|---|---|---|
| Nausea/vomiting (morning sickness) | 6-12 weeks | Small frequent meals, ginger, B6 (25 mg q6-8h), doxylamine (Unisom) 12.5-25 mg hs |
| Fatigue | 1st and 3rd trimester | Rest, adequate sleep, iron check if severe |
| Heartburn/GERD | 2nd and 3rd trimester | Small meals, avoid trigger foods, antacids, H2 blockers, PPIs if needed |
| Constipation | Throughout | Increase fiber, fluids, exercise; stool softeners if needed |
| Hemorrhoids | 2nd and 3rd trimester | Stool softeners, sitz baths, witch hazel pads |
| Round ligament pain | 2nd trimester | Position changes, support, warm compresses |
| Back pain | Throughout | Good posture, support belt, physical therapy, acetaminophen |
| Leg cramps | 2nd and 3rd trimester | Stretching, magnesium, hydration |
| Varicose veins | 2nd and 3rd trimester | Elevation, compression stockings |
| Edema (swelling) | 2nd and 3rd trimester | Elevation, hydration, avoid prolonged standing; assess for preeclampsia |
| Urinary frequency | 1st and 3rd trimester | Limit fluids before bed; rule out UTI |
| Shortness of breath | 3rd trimester | Elevate head of bed; assess if sudden or severe |
| Braxton Hicks contractions | 3rd trimester | Hydration, position changes; distinguish from preterm labor |
Warning Signs
Signs Requiring Immediate Medical Attention
| Symptom | Possible Condition |
|---|---|
| Vaginal bleeding | Placenta previa, abruption, miscarriage, preterm labor |
| Severe abdominal/pelvic pain | Ectopic pregnancy, abruption, preterm labor, placental issues |
| Leaking fluid (gush or trickle) | Rupture of membranes |
| Decreased fetal movement (<10 movements in 2 hours after 28 weeks) | Fetal distress |
| Severe headaches (especially with visual changes) | Preeclampsia |
| Visual disturbances (blurring, double vision, floaters) | Preeclampsia, migraine |
| Right upper quadrant/epigastric pain | HELLP syndrome, preeclampsia |
| Chest pain with dyspnea | Pulmonary embolism, peripartum cardiomyopathy |
| Calf pain/swelling (unilateral) | Deep vein thrombosis |
| Fever >100.4F (38C) with chills | Infection (chorioamnionitis, UTI, pneumonia) |
| Painful urination or blood in urine | Urinary tract infection, pyelonephritis |
| Persistent vomiting (unable to keep fluids down) | Hyperemesis gravidarum |
| Severe edema (face, hands, sudden) | Preeclampsia |
| Syncope or near-syncope | Ectopic, hemorrhage, cardiac issues |
Prenatal Testing
First Trimester Screening (11-14 weeks)
| Test | Components | Detection Rate | False Positive Rate |
|---|---|---|---|
| Nuchal translucency (NT) ultrasound | Fluid at back of fetal neck | 70-80% (aneuploidy) | 5% |
| Combined first-trimester screen | NT + PAPP-A + free beta-hCG | 85-90% (T21), 75% (T18) | 5% |
| cfDNA/NIPT (cell-free fetal DNA) | Fetal DNA from maternal blood | >99% (T21), >97% (T18/T13) | <0.1% |
| Chorionic villus sampling (CVS) | Placental tissue sampling | 99% (diagnostic) | 1% risk miscarriage |
Second Trimester Screening (15-22 weeks)
| Test | Components | Detection Rate | Notes |
|---|---|---|---|
| Quad screen | AFP, hCG, uE3, Inhibin A | 75-80% (T21), 80% (open neural tube defects) | Can identify neural tube defects |
| Anatomy ultrasound (18-22 weeks) | Detailed fetal anatomy | Variable | Identifies structural anomalies |
| Amniocentesis | Amniotic fluid analysis | >99% (diagnostic) | 1/500-1/1000 risk miscarriage |
Cell-Free Fetal DNA (NIPT/NIPS)
| Aspect | Detail |
|---|---|
| Optimal timing | After 10 weeks |
| Screens for | Trisomy 21 (Down), 18 (Edwards), 13 (Patau); optional: sex chromosome aneuploidies, microdeletions |
| Detection rate | T21: >99%, T18: 97-98%, T13: 90-95% |
| False positive rate | <0.1% (T21), higher for T13 and microdeletions |
| Positive predictive value | Varies with age and prevalence (lower in low-risk population) |
| Limitations | Screening test (not diagnostic); may fail in multiple gestations, maternal mosaicism, BMI >40 |
Glucose Tolerance Testing
| Test | Timing | Protocol | Diagnosis |
|---|---|---|---|
| 1-hour screening (50g) | 24-28 weeks | Non-fasting, plasma glucose at 1 hour | >130-140 mg/dL -> 3-hour GTT |
| 3-hour diagnostic (100g) | 24-28 weeks | Fasting; glucose at 0, 1, 2, 3 hours | 2+ values elevated: GDM |
| Early screening | First visit | If risk factors (prior GDM, obesity, PCOS) |
GDM Diagnostic Criteria (Carpenter-Coustan)
| Time | Plasma Glucose Threshold |
|---|---|
| Fasting | >95 mg/dL |
| 1 hour | >180 mg/dL |
| 2 hours | >155 mg/dL |
| 3 hours | >140 mg/dL |
Group B Streptococcus (GBS) Screening
| Aspect | Detail |
|---|---|
| Timing | 36-37 weeks |
| Method | Vaginal and rectal swab |
| Prevalence | 10-30% of women are colonized |
| Significance | GBS is leading cause of neonatal sepsis |
| Treatment | IV penicillin or ampicillin during labor (if positive, or if risk factors) |
| Penicillin allergy | Cefazolin (if low risk), clindamycin/vancomycin (if high risk) |
Medications in Pregnancy
| Category | FDA Classification (Old) | FDA Labeling (New, 2015+) |
|---|---|---|
| A | Controlled studies show no risk | Narrative summary of risk |
| B | No evidence of risk in humans, but no controlled studies | Includes pregnancy exposure registry |
| C | Risk cannot be ruled out | Risk summary, clinical considerations |
| D | Positive evidence of risk (may be justified) | Data |
| X | Contraindicated |
Pregnancy-Safe Medications for Common Conditions
| Condition | Safe Options | Avoid |
|---|---|---|
| Pain/fever | Acetaminophen (lowest effective dose, shortest duration) | NSAIDs (especially 3rd trimester), aspirin (high dose) |
| Nausea | B6, doxylamine, ondansetron, metoclopramide | (Generally good safety profiles) |
| GERD | Antacids, H2 blockers, PPIs | (Generally safe) |
| Constipation | Stool softeners (docusate), fiber, polyethylene glycol | Castor oil |
| Allergies | Loratadine, cetirizine, diphenhydramine (PRN) | (Generally safe) |
| Urinary tract infection | Penicillins, cephalosporins, nitrofurantoin | Fluoroquinolones, tetracyclines |
| Psychiatric (depression) | SSRIs (sertraline, fluoxetine preferred); avoid paroxetine | Paroxetine (increased risk of cardiac defects) |
| Hypertension | Labetalol, nifedipine, methyldopa | ACE inhibitors, ARBs (especially 2nd/3rd trimester) |
| Diabetes | Insulin (preferred), metformin, glyburide | Oral agents with limited safety data |