Pregnancy nutrients by week and trimester

The reference amounts at a glance (United States)

These are the values the NIH Office of Dietary Supplements (ODS) publishes for pregnancy. They are population reference values set by the Food and Nutrition Board. They are not a personal target. The American College of Obstetricians and Gynecologists (ACOG) lists the same figures in its patient FAQ.

Two things to know about this table. "RDA" means Recommended Dietary Allowance. "AI" means Adequate Intake, which is used when there is not enough evidence to set an RDA; choline and omega-3 have AIs, not RDAs. There is no US RDA for DHA on its own; the omega-3 value above is for ALA, a plant omega-3.

ACOG's patient FAQ adds three more values for pregnancy: vitamin A 770 micrograms, vitamin C 85 milligrams and vitamin B6 1.9 milligrams for ages 19 to 50 (vitamin A 750 micrograms and vitamin C 80 milligrams for ages 14 to 18).

What changes by week

The amounts above stay the same across all three trimesters. The timing advice does not. Here is what the public sources tie to a week or a window.

How to read this by trimester:

• First trimester (weeks 1 to 13). Folic acid is the nutrient the sources time most precisely. ACOG and the NHS both point to the first 12 weeks. ACOG notes that during pregnancy the folate figure is 600 micrograms a day, and that "it's hard to get this much folic acid from food alone."
• Second trimester (weeks 14 to 27). No reference amount changes. Glucose screening, which ACOG places between 24 and 28 weeks, is when many people bring food questions to a visit.
• Third trimester (weeks 28 to 40). The NHS schedules an iron blood test at the 28-week appointment. In the US, ACOG notes an Rh antibody screen may be repeated at 28 weeks for Rh-negative people (see our prenatal visit questions by week page). The reference amounts still do not change.

Niva's own week-by-week food prompts follow this same logic: the daily reference does not move, so the app rotates which food ideas it shows rather than changing any target.

Nutrient by nutrient

Folate and folic acid

• Pregnancy RDA: 600 mcg DFE a day. The NIH ODS fact sheet says the Food and Nutrition Board "increased the folate RDA from 400 mcg DFE/day for nonpregnant women to 600 mcg DFE/day during pregnancy." (NIH ODS)
• Supplement amount before pregnancy: 400 mcg a day. "Women of childbearing age should obtain 400 mcg/day folic acid from dietary supplements and/or fortified foods in addition to the folate provided by a varied diet." (NIH ODS) The CDC says the same: "All women capable of becoming pregnant should get 400 micrograms (mcg) of folic acid daily." (CDC)
• A wider US range exists. The NIH ODS sheet reports that the US Preventive Services Task Force recommends a "daily supplement containing 400 to 800 mcg folic acid starting least 1 month before conception." (NIH ODS)
• After a previous pregnancy affected by a neural tube defect, the figures are much higher and are a care-team decision. CDC: "The current recommendation is to get 4,000 mcg of folic acid every day." (CDC) ACOG: "4 milligrams (mg) of folic acid each day as a separate supplement at least 3 months before pregnancy and for the first 3 months of pregnancy." (ACOG) NHS: "A higher dose is 5 milligrams (5mg)." (NHS) These doses exceed the upper limit below and the NIH says they "should be taken only under medical supervision."
• Upper limit for folic acid from supplements and fortified foods: 1,000 mcg a day for ages 19 and over, including pregnancy. The limit does not apply to folate from food. (NIH ODS, Table 3)
• Food sources ACOG lists: "Fortified cereal, enriched bread and pasta, peanuts, dark green leafy vegetables, orange juice, beans." (ACOG)

Iron

• Pregnancy RDA: 27 mg a day (ages 14 to 50). Outside pregnancy the figure for ages 19 to 50 is 18 mg. (NIH ODS, Table 1)
• Why it rises. "During pregnancy, plasma volume and red cell mass expand as maternal red blood cell production increases to meet the needs of the fetus and placenta." (NIH ODS)
• ACOG on prenatal vitamins: "When you are pregnant, you need 27 mg per day. You can get this amount in most prenatal vitamins." (ACOG)
• Upper limit: 45 mg a day for ages 14 and over, including pregnancy. (NIH ODS, Table 3)
• Canada frames it as a supplement amount: "take a daily multivitamin that contains 16 to 20 mg of iron." (Public Health Agency of Canada)
• The UK checks rather than counts. The NHS page on vitamins gives no daily iron figure; its appointment schedule includes a 28-week blood test for "iron levels." (NHS)

Calcium

• Pregnancy RDA: 1,000 mg a day for ages 19 to 50; 1,300 mg for ages 14 to 18. These are the same values as for people of the same age who are not pregnant. (NIH ODS, Table 1)
• ACOG puts it the same way: "If you are 18 or younger, you need 1,300 mg of calcium per day. If you are 19 or older, you need 1,000 mg per day." (ACOG)
• Upper limit: 2,500 mg a day for ages 19 to 50; 3,000 mg for ages 14 to 18. (NIH ODS, Table 3)
• Food sources ACOG lists: "Milk and other dairy products, such as cheese and yogurt, are the best sources of calcium," and for people who have trouble digesting milk, other sources "such as broccoli" and fortified cereals and breads. (ACOG)

Vitamin D

• Pregnancy RDA: 15 mcg (600 IU) a day, the same as for non-pregnant adults aged 19 to 70. (NIH ODS, Table 2) ACOG: "Whether you are pregnant or not, you need 15 mcg (600 international units [IU]) of vitamin D a day." (ACOG)
• Upper limit: 100 mcg (4,000 IU) a day for ages 9 and over, including pregnancy. (NIH ODS, Table 4)
• The UK figure is different. The NHS says to take "10 micrograms of vitamin D every day between early October and late March," year-round for people with limited sun exposure or darker skin, and "Do not take more than 100 micrograms of vitamin D a day." (NHS) So the US reference is 15 mcg daily all year and the UK supplement advice is 10 mcg, seasonally for most people. Both set 100 mcg as the ceiling.
• Food sources ACOG lists: "fortified milk and breakfast cereal, fatty fish (salmon and mackerel), fish liver oils, and egg yolks." (ACOG)

Choline

• Pregnancy Adequate Intake: 450 mg a day (ages 14 to 50). (NIH ODS, Table 1) ACOG: "Experts recommend that you get 450 mg of choline each day during pregnancy." (ACOG)
• Why it is on this page. The NIH notes that "Approximately 90%–95% of pregnant women consume less choline than the AI" and that "Prenatal dietary supplements typically contain little if any choline." (NIH ODS) That is a population finding, not a statement about you.
• Upper limit: 3,500 mg a day for ages 19 and over, including pregnancy. (NIH ODS, Table 3)
• Food sources ACOG lists: "chicken, beef, eggs, milk, soy products, and peanuts." (ACOG)

Iodine

• Pregnancy RDA: 220 mcg a day. "During pregnancy, the RDA for iodine increases from 150 to 220 mcg/day." (NIH ODS)
• The World Health Organization sets a higher figure. The NIH sheet notes that WHO, UNICEF and the International Council for the Control of Iodine Deficiency Disorders "recommend a slightly higher iodine intake for pregnant women of 250 mcg per day." (NIH ODS)
• Upper limit: 1,100 mcg a day for ages 19 and over, including pregnancy. (NIH ODS, Table 3)
• The NIH also notes that "Pregnant women who do not consume dairy products may be particularly at risk of iodine insufficiency." (NIH ODS) If that describes you, it is a good question for your care team.

Omega-3 fats, DHA and seafood

• There is no US RDA for DHA. The only US reference value is an Adequate Intake of 1.4 g a day of ALA (a plant omega-3) in pregnancy. (NIH ODS, Table 1)
• Seafood is where the sources agree. ACOG: "You should eat two or three servings of fish or shellfish per week before getting pregnant, while pregnant, and while breastfeeding. A serving of fish is 4 ounces (oz)." (ACOG) FDA: those who are pregnant or breastfeeding "consume between 8 and 12 ounces per week," where "1 serving is 4 ounces," choosing from its "Best Choices" list. (FDA) The NIH summarizes ACOG, FDA and the Dietary Guidelines as all saying "Consume 8–12 ounces/week of seafood that is lower in mercury." (NIH ODS, Table 3)
• Europe gives a DHA number; the US does not. The NIH table records the European Food Safety Authority advice to "Consume an additional 100–200 mg/day DHA during pregnancy on top of 250 mg/day of DHA plus EPA for all adults." (NIH ODS, Table 3)
• Fish ACOG says to skip: "Do not eat bigeye tuna, king mackerel, marlin, orange roughy, shark, swordfish, or tilefish. Limit white (albacore) tuna to only 6 oz a week." (ACOG)
• Plant sources ACOG lists: flaxseed, "broccoli, cantaloupe, kidney beans, spinach, cauliflower, and walnuts." (ACOG)

Vitamin B12

• Pregnancy RDA: 2.6 mcg a day, up from 2.4 mcg outside pregnancy. (NIH ODS, Table 1) ACOG lists the same 2.6 micrograms. (ACOG)
• ACOG notes that B vitamins come from foods "including liver, pork, chicken, bananas, beans" and whole grains, and that "Your prenatal vitamin should have the right amount of B vitamins that you need each day." (ACOG) If you eat little or no animal food, B12 is worth raising with your care team.

Where the US, UK and Canada differ

Why the differences exist is beyond this page. The honest summary is that the US, UK and Canadian bodies set these figures separately and do not always land on the same number. If you live in one country and read advice from another, bring both to your care team.

Questions to bring to your care team

• Does my prenatal vitamin cover folic acid, iron, iodine and choline, and does my history change anything about it?
• My blood work: when is iron checked, and what did the last result show?
• I eat little or no dairy, fish, or animal foods. Which of these nutrients should we talk about?
• I have had a pregnancy affected by a neural tube defect, or I take medicine for epilepsy or diabetes. Does the folic acid amount change for me?
• Nausea, reflux or constipation make eating hard. What is a realistic plan for the next few weeks?

What this page does not do

It does not tell you what is enough, what is safe, or what your body needs. It does not replace a visit. If a number here differs from what your care team told you, your care team's advice is the one to follow.

Niva is a pregnancy tracker and wellness app for iPhone that keeps week-by-week food ideas and visit questions in one place, so you arrive at each appointment with your own list. Free to download. Optional Niva Plus. Available in the US and Canada on the App Store.