What dietary restrictions and recommendations are advised during the 1st trimester of pregnancy?

First Trimester Dietary Restrictions and Recommendations

All women in the first trimester should take 400 µg/day of folic acid supplementation (or 5 mg/day if obese or diabetic) and avoid vitamin A in retinol form, raw animal products, soft cheeses, alcohol, and excessive caloric intake, while ensuring adequate protein, iron, and balanced nutrition. 1

Essential Supplementation in First Trimester

Folic Acid (Critical Priority)

• Standard dose: 400 µg/day from fortified foods and/or supplements, starting before conception and continuing through at least the 12th week of pregnancy 1, 2
• Higher dose (5 mg/day) is required for women with obesity or diabetes 1
• This prevents neural tube defects and other congenital abnormalities 1
• Folic acid supplementation is the single most important dietary intervention in early pregnancy 2, 3

Vitamin B12 Monitoring

• Vitamin B12 should be measured during the preconception period before additional folic acid supplements are given 1, 4
• This is critical because high-dose folic acid (>1000 µg/day) without adequate B12 may mask vitamin B12 deficiency, potentially allowing neurological symptoms to progress to irreversible deficits 4, 2

Iron

• Low-dosage iron supplementation (30 mg/day) is often recommended, though typically started in the second and third trimesters 1
• Iron supplementation in the first trimester should be based on medical history and blood testing 3

Iodine

• Iodine-rich foods and iodized salt plus an iodine supplement (100-150 µg/day) are recommended 3

Vitamin D

• Vitamin D supplementation is advisable unless there is regular exposure to sunlight 3

Critical Dietary Restrictions in First Trimester

Vitamin A (Retinol Form) - AVOID

• Women should avoid vitamin and mineral preparations containing vitamin A in the retinol form during the first 12 weeks of pregnancy 1
• Excess retinoic acid increases teratogenic risk, especially in the first trimester 1
• Beta-carotene form of vitamin A is safe and preferred over retinol 1
• If supplementation is needed post-bariatric surgery, restrict vitamin A intake to 5,000-10,000 IU/day 1

Food Safety - Infection Prevention

• Avoid raw animal foods, soft cheeses, and packed fresh salads to reduce risk of listeriosis and toxoplasmosis 3
• Fresh fruit, vegetables, and salad should be washed well and consumed promptly 3

Alcohol

• Avoid alcohol completely - no amount is considered safe during pregnancy 1, 5, 3

Caffeine

• Up to 3 daily cups of coffee are considered harmless 3
• Energy drinks should be avoided 3

Energy and Macronutrient Requirements

First Trimester Energy Needs

• Energy needs do not increase in the first trimester unless a woman begins pregnancy with depleted body reserves 1
• Normal-weight women should gain 1.4-2.3 kg during the first trimester 1
• For obese women (BMI >30 kg/m²), a relatively small total pregnancy weight gain of 7 kg is recommended 1

Protein Requirements

• Protein requirements are 0.75 g/kg/day plus an additional 10 g/day during pregnancy 1
• Pregnant women need to eat a balanced diet with adequate protein 1

Avoiding Ketosis

• Hypocaloric diets (<1,200 calories per day) should be avoided as they result in ketonemia and ketonuria 1
• Ketonemia has been associated with lower intelligence scores in offspring at ages 2-5 years 1
• An evening snack is usually necessary to decrease the potential for overnight hypoglycemia and fasting ketosis 1

Additional Micronutrient Considerations

Zinc

• The RDA for zinc during pregnancy is 15 mg/day, while average intake is only 11 mg/day 1
• Zinc supplementation for women with low pregravid weight and low plasma zinc levels leads to infants with higher birth weight 1

Calcium

• A balanced diet resulting in appropriate weight gain generally supplies adequate calcium 1
• However, many pregnant women have inadequate calcium intake and may require supplementation 6, 7

Nonnutritive Sweeteners

• FDA-approved nonnutritive sweeteners (saccharin, aspartame, acesulfame-K, and sucralose) appear safe for use during pregnancy, though moderation is recommended 1, 2

Special Population Considerations

Post-Bariatric Surgery Patients

• Women post-bariatric surgery should undergo nutritional screening every trimester, including ferritin, folate, vitamin B12, calcium, vitamin D, and vitamin A 1
• More frequent review with a specialist bariatric dietitian may be required 1
• Vitamin B12 levels should be monitored every trimester with supplementation adjusted to maintain normal serum concentrations 4

Vegetarian and Vegan Diets

• Vegetarian diets with nutritional supplements can provide adequate nutrition, but counseling is recommended 3
• Vegan diets are inadequate and require additional micronutrient supplementation 3

Common Pitfalls to Avoid

• Do not prescribe high-dose folic acid without first checking vitamin B12 status - this can mask pernicious anemia while neurological damage progresses 4, 2
• Do not recommend severe caloric restriction - even in obese women, energy intake should not drop below 1,200 kcal/day to avoid ketosis 1
• Do not assume prenatal vitamins alone are sufficient - many women still have inadequate intake of key nutrients despite supplementation 6, 8
• Food is considered the optimal vehicle for nutrient intake, though prenatal vitamin and mineral supplements are often prescribed because of uncertainty of nutritional status and intake 1