Folate is the most critical nutrient. It prevents neural tube defects, which form within the first 28 days of pregnancy. Foods rich in folate include dark leafy greens, dal, and fortified cereals. A folic acid supplement of 400 to 800 micrograms daily is recommended from before conception through the first trimester.
Nausea in the first trimester often makes eating difficult. Small, frequent meals with mild flavours tend to be better tolerated than large meals. Staying hydrated is more important than eating a varied diet in the first weeks.