“What vitamins to avoid during the second trimester?”
I am in my second trimester. What vitamins to avoid during the second trimester?
3 Answers
Dietitian-NutritionistDietitian-Nutritionist
Great question — you're doing the right thing by double-checking what’s safe during pregnancy. In the second trimester, most standard prenatal vitamins are not only safe but recommended. However, there are certain vitamins and supplements that should be avoided or taken with caution to avoid excessive dosing or potential harm to you or your baby.
Vitamins & Supplements to Avoid or Limit in the Second Trimester
1. Vitamin A (Retinol) – in high doses
Why: High doses of preformed vitamin A (retinol, found in some acne treatments and liver supplements) can be teratogenic (cause birth defects).
Safe form: Beta-carotene (the plant-based version) is safe; most prenatals use this.
Limit: Avoid more than 10,000 IU (3,000 mcg RAE) of vitamin A daily from all sources.
2. Vitamin E (in large doses)
Why: Some studies suggest high-dose vitamin E may be associated with increased risk of abdominal pain and premature rupture of membranes.
Limit: Stick to what’s in your prenatal unless your provider specifically recommends more.
3. Herbal supplements or "natural" vitamins not studied in pregnancy
Why: Many herbal products (like dong quai, black cohosh, ginseng, or vitex) can interfere with hormones or uterine function.
Caution: Always ask your provider before starting any herbal or non-standard supplements.
4. High-dose Iron (unless prescribed)
Why: Too much iron can cause constipation, nausea, and interfere with absorption of other nutrients.
Note: Most prenatals have the right amount (27 mg); don’t add more unless you're anemic and your doctor recommends it.
5. Vitamin B6/B12 in megadoses
Why: While B6 is often used for nausea, very high doses (>100 mg/day) can cause nerve problems. B12 is generally safe, but don’t exceed mega-doses without supervision.
What You Should Be Taking in the Second Trimester:
A high-quality prenatal vitamin with:
Folate (L-methylfolate or folic acid) – 400–800 mcg
Iron – ~27 mg
Calcium + magnesium – for bone and muscle support
Vitamin D3 – 1000–2000 IU daily
DHA (omega-3) – 200–300 mg for fetal brain and eye development
Choline – ideally 250–350 mg/day for neural development (may need separate supplement)
Vitamins & Supplements to Avoid or Limit in the Second Trimester
1. Vitamin A (Retinol) – in high doses
Why: High doses of preformed vitamin A (retinol, found in some acne treatments and liver supplements) can be teratogenic (cause birth defects).
Safe form: Beta-carotene (the plant-based version) is safe; most prenatals use this.
Limit: Avoid more than 10,000 IU (3,000 mcg RAE) of vitamin A daily from all sources.
2. Vitamin E (in large doses)
Why: Some studies suggest high-dose vitamin E may be associated with increased risk of abdominal pain and premature rupture of membranes.
Limit: Stick to what’s in your prenatal unless your provider specifically recommends more.
3. Herbal supplements or "natural" vitamins not studied in pregnancy
Why: Many herbal products (like dong quai, black cohosh, ginseng, or vitex) can interfere with hormones or uterine function.
Caution: Always ask your provider before starting any herbal or non-standard supplements.
4. High-dose Iron (unless prescribed)
Why: Too much iron can cause constipation, nausea, and interfere with absorption of other nutrients.
Note: Most prenatals have the right amount (27 mg); don’t add more unless you're anemic and your doctor recommends it.
5. Vitamin B6/B12 in megadoses
Why: While B6 is often used for nausea, very high doses (>100 mg/day) can cause nerve problems. B12 is generally safe, but don’t exceed mega-doses without supervision.
What You Should Be Taking in the Second Trimester:
A high-quality prenatal vitamin with:
Folate (L-methylfolate or folic acid) – 400–800 mcg
Iron – ~27 mg
Calcium + magnesium – for bone and muscle support
Vitamin D3 – 1000–2000 IU daily
DHA (omega-3) – 200–300 mg for fetal brain and eye development
Choline – ideally 250–350 mg/day for neural development (may need separate supplement)
Half way there!
Unless you have any medications/supplements prescribed by your OB/GYN, just continue taking your daily prenatal vitamin.
Unless you have any medications/supplements prescribed by your OB/GYN, just continue taking your daily prenatal vitamin.
Thank you for your question. First, I wish to congratulate you on this pregnancy. Hopefully you may be beyond the morning sickness often associated with early stages of pregnancy. Regarding advice for what to take & what not to take during one's pregnancy is best discussed with your prenatal care provider. Such matters can be associated with your underlying health factors & that of your baby. Best wishes to you for a happy & healthy pregnancy. With your next prenatal visit, or ask this question of your provider with a call to the office whichever is sooner. GABrowne MD. FRC
