If you're a sexually active woman not using birth control, it's best to always eat as if you might be pregnant. Even if you're using a fairly reliable method, such as oral contraceptives, failures can and do occur; if you get pregnant unexpectedly, having good nutrition on board can make a difference for your baby-to-be even in the first few weeks, before you realize you're pregnant. Of course, if you're actively trying to get pregnant, making sure you're well nourished is even more important than stocking up on ovulation predictor kits and pregnancy tests.
The First Four Weeks of Pregnancy
Whoever came up with the system for measuring the weeks of pregnancy created a great deal of confusion. Pregnancy is measured as 40 weeks, but the first week starts at the beginning of your last period. Obviously, you're not even pregnant in the first week; in fact, you don't even ovulate until the end of the second week of pregnancy — if you get pregnant. The embryo implants in week three and at the end of week four, you realize your period isn't showing up on time. So you're really only pregnant for the last week or so of the first four weeks of pregnancy — but it's an important week, nutritionally speaking.
Many doctors recommend that all women of childbearing age take 400 micrograms of the B-complex vitamin folic acid daily — just in case of a "whoops" pregnancy. Women who take folic acid in the months before they get pregnant through the first few weeks of pregnancy reduce the risk of having a baby with neural tube defects such as spina bifida or anencephaly — a small or absent brain -- by as much as 70 percent, according to the March of Dimes. Leafy green vegetables, such as spinach and kale, as well as broccoli, lentils, fortified cereals and black beans, contain folic acid, but if you want to make sure you're getting enough, take a multivitamin.
Mild iron deficiency affects as many as 35 to 58 percent of all women of childbearing age. If you have low iron stores, that could affect your baby in the early part of pregnancy. A 2011 University of Rochester study found that having low iron stores in the weeks before you get pregnant and into the first weeks of pregnancy can have a negative effect on a developing baby's brain. Boost your iron stores before you get pregnant by eating foods high in iron, such as meat, poultry or fish. Eat vegetables high in iron, such as spinach and other leafy greens, along with foods high in vitamin C, such as orange juice, which can up your absorption of iron from foods.
Starting the day with a mug of caffeine in the form of a hot or cold beverage is a common habit among women of childbearing age. And — as with many things — caffeine in moderation won't hurt you or your baby. But if you overindulge in lattes or cappuccino to the point at which your caffeine intake exceeds 200 milligrams per day, you could possibly double your risk of having a miscarriage. You would have to down more than 16 ounces of brewed coffee per day to exceed that amount, but if you're a serious caffeine junkie, cut back to no more than two cups per day.
Alcohol in large quantities can cause severe birth defects in a fetus, but many a just-diagnosed pregnant mom-to-be has agonized needlessly over the drinks she had the week before she found out she was pregnant -- or the night of conception. While large amounts of alcohol in the third and fourth week of pregnancy might prevent conception or cause a very early miscarriage, an embryo is relatively resistant to developing malformations in the first four weeks of pregnancy, according to the textbook "Gynecology and Obstetrics." Fetal alcohol syndrome and other malformations most commonly occur if you drink heavily between weeks 7 and 12, a 2012 University of California, San Diego study reported. Once you know you're pregnant, abstinence is the safest policy.
Suzanne Robin is a registered nurse with more than 25 years of experience in oncology, labor/delivery, neonatal intensive care, infertility and ophthalmology. She also has extensive experience working in home health with developmentally delayed or medically fragile children. Robin received her RN degree from Western Oklahoma State College. She has coauthored and edited numerous books for the Wiley "Dummies" series.