Folic acid supplementation in the second + third trimesters

It is very important to ensure adequate folic acid intake from 3 months before conception to the end of the first trimester. For most of us that means taking a prenatal vitamin (tricky because that’s usually when we are the LEAST interested in popping pills). My question, however, is how important is it to take folic acid supplements in the second and third trimester?

It is well documented that folic acid supplementation and food fortification reduces the incidence of neural tube defects such as spina bifida. The research about the importance of folic acid supplementation beyond the first trimester is less clear, and in fact, there is a little research to show that perhaps we don’t want extremely high levels later in pregnancy. It may increase the risk of allergy, and also may be correlated with increased risk of autism. There is definitely not enough research yet to draw any conclusions, but I would say that it’s safe to get a little sloppy with your daily prenatal supplement after the first trimester. Dosing of 3-5x per week seems to be safe, and the baby is really growing LOTS later in the pregnancy, so you want to make sure the little one has access to all of the other nutrients needed for development.

The best bet is to skip a couple doses of prenatal vitamins each week (after the first trimester), and be sure that you have a very nutrient dense diet to act as a safety net.

Here are some dietary sources of folic acid to include in your diet:

Table I This table charts the sources of dietary folate from different food.
Food 1 Food Guide Serving Micrograms of folate as dietary folate equivalents (µg DFEs)
Lentils and romano beans 175 mL 265-270
Black beans 175 mL 190
Okra 125 mL 140
White beans 175 mL 125
Asparagus and spinach, cooked 125 mL 120
Salad greens, such as Romaine lettuce, mustard greens and endive 250 mL 80-110
Pinto beans, kidney beans and chickpeas 175 mL 70-100
Pasta made with enriched wheat flour 125 mL 90
Avocado ½ fruit 80
Sunflower seeds, shelled 60 mL 80
Bagel made with enriched wheat flour ½ bagel (45 g) 60-75
Brussels sprouts, beets and broccoli, cooked 125 mL 70
Bread made with enriched wheat flour or enriched corn meal 1 slice or ½ pita or ½ tortilla (35 g) 45-65
Spinach, raw 250 mL 60
Orange juice from concentrate 125 mL 60
Parsley 125 mL 50
Parsnips 125 mL 50
Peanuts, shelled 60 mL 45
Eggs 2 large 45
Corn 125 mL 40
Seaweed 125 mL 40
Orange 1 medium 40
Green peas 125 mL 40
Raspberries, strawberries, blackberries 125 mL 15-35
Enriched ready to eat cereal 30 g 10-35
Broccoli and cauliflower, raw 125 mL 30
Snow peas 125 mL 30
Pineapple juice 125 mL 30
Walnuts, almonds and hazelnuts, shelled 60 mL 20-30
Baby carrots 125 mL 25
Kiwifruit 1 large 20
Clementine 1 fruit 20

Other important supplements in pregnancy include:

  • Omega 3 fatty acids for brain development (DHA in particular)
  • Vitamin D if you are deficient (mostly to ensure adequate levels in breastmilk postpartum)
  • Calcium and magnesium after the first trimester to support bone development and to protect mom’s bones, as well as prevent leg cramping later in pregnancy