Folic acid (folate ) is a B vitamin discovered to be a vitally important food ingredient both before conception and during the first trimester of pregnancy if neural tube defects like spina bifida and possible consequent hydrocephalus are to be avoided. Good sources of folate include many vegetables - especially leafy greens - and fruits such as blackberries, strawberries, kiwi fruit ; as well as fruit juices e.g. of oranges and pineapples. Improvement of diet quality through use of nutritious foods is strongly preferred to supplementation. Foods supply energy and essential nutrients not found in supplements, and there is less risk of undesirable nutrient-nutrient interactions when nutrients are provided by foods. Nonetheless, certain situations may warrant use of a multivitamin-mineral supplement, which should be taken between meals or at bedtime in order to promote more efficient absorption. Women who seldom ingest many green vegetables, fruit (juices) or whole-grain / fortified cereals could benefit from ~ 300 micrograms daily folate supplement. Data collected internationally by the U.S. Dept. of Health & Human Services supports the view that dietary intake by pregnant women is commonly less than the RDA for eight nutrients :- notably vitamins B₆ , D , E , folate , iron , zinc , calcium and magnesium : and the use of sbstances such as tobacco, alcohol, caffeine, marijuana, or cocaine may affect maternal nutrition by increasing actual need for one or more nutrients through a variety of mechanisms; e.g. by increasing urinary excretion or by leading to undesirable changes in food and nutrient intake. Pregnant women who do not ordinarily consume an adequate diet or who are in higher-risk categories (e.g. carrying more than one fetus, heavy cigarette smokers, alcohol and drug abusers) are especially recommended to take a multivitamin-mineral preparation.

There is no evidence of substantial differences in nutrient requirements among the various ethnic groups, but ethnic differences in food choices and consequently in the mean intake of certain nutrients do exist. For example ethnic groups with a high prevalence of lactose intolerance customarily consume less milk, so their intakes of calcium & vitamin D deserve special attention. Also among women under 25 the adequacy of Ca and vitamin D should receive attention , because bone mineral density is still increasing during that period of life. For those whose daily dietary Ca intake is <600mg - a supplement of ~ 600mg is recommended, ( preferably at mealtime so that interaction with Fe⁺⁺ supplements is minimised ) : but for older women who become pregnant there is no evidence that raised Ca intake will protect against later bone loss by osteoporosis. At high latitudes in winter exposure to sunlight is likely to be insufficient for any appreciable synthesis of vitamin D by the skin and for complete vegetarians a daily supplement of 10 micrograms (400 IU) is advisable throughout the year. Complete vegetarians are also recommended a 2 microgram daily supplement of vitamin B₁₂ . When therapeutic levels of iron ( >30mg / day ) are given to treat anaemia - supplementation with ~15mg Zn and 2mg Cu is recommended as the Fe⁺⁺ may interfere with absorption of those trace elements. For the general population of pregnant women, daily supplements of ~ 30mg ferrous iron are recommended during 2nd and 3rd trimesters - e.g. from taking ferrous sulphate , fumarate or gluconate. Constipation , a side effect of such iron supplementation ( as well as of progesterone-induced relaxation of bowel muscles ) may often be mitigated by ensuring raised levels of dietary fibre. Alternatively, capsules or tablets of chlorophyll may be taken prenatally - both to raise low hemoglobin and promote clotting factor, as well as act as a gentle laxative.

Whereas increased use of protein foods is expected, routine ingestion of specially formulated high-protein supplements or beverages is not recommended and and may be harmful during pregnancy.