First comes the thrill of a positive pregnancy test. Next comes the fretting. Whether you're a first-time mom or have been through childbirth on more than one occasion, every mother-to-be has concerns. The most important thing you can do for yourself and your soon-to-be-born baby is to feed yourself - and by extension, your little one - very well. Not too long ago, nutrition during pregnancy was a matter of don'ts - a laundry list of foods to avoid. Today, midwives and obstetricians take a far more positive approach to eating during pregnancy. Now that you're eating for two, these nutrition tips can help you feed your baby properly during one of the most critical periods of development - before birth.

Keep it Fresh

The first to-do is a matter of common sense. Whenever possible, choose fresh foods rather than packaged, processed or canned foods. It may seem like a burden, but fresh vegetables and fruits aren't any more difficult to prepare than processed alternatives. However, they have the added benefit of providing far more nutrition with far fewer chances of toxins. Choose whole grain breads and cereals instead of sugary processed breakfast cereals and add fresh, cut fruit to plain yogurt instead of choosing sweetened fruit-flavored options. The latter are higher in calories and lower in nutrition.

Add Healthy Snacks to Your Diet

A pregnant mother needs to increase her calorie intake by 15 to 25 percent to provide enough nutrition for the baby's proper growth. At the same time, pregnancy can leave you feeling queasy and uncomfortable, especially if you eat a full meal. One of the best ways to deal with the dual challenge of eating more - and better - calories when your body just doesn't feel like it is to eat less food more often. Add mid-morning and mid-afternoon snacks to your daily routine. A piece of fruit, a handful of nuts or a yogurt smoothie add both high quality nutrients and more calories to your diet without triggering morning sickness.

Add Leafy Greens to Your Meals

Folate is vital for your baby's healthy development. Mothers who don't get enough dietary folate during certain periods of their pregnancies put their children at risk for neural tube defects, including spina bifida. Spinach, turnip greens and collard greens are excellent sources of folate. If you just can't tolerate those deliciously bitter, leafy greens, you can also get folate from sunflower seeds, edamame, bean sprouts, dried beans, liver and asparagus. And just to be sure, you can also take a prenatal vitamin that contains B vitamins.

Learn to Love Fatty Fish

Fatty fish, such as tuna and salmon, provide several essential nutrients that your developing baby craves - vitamin D, calcium and vitamin B among them - but tuna can also carry high levels of mercury. Eat salmon or fresh-caught tuna from northern waters two to three times a week.

Calcium Starts Building Strong Bones Before Birth

Lose a tooth with every child, goes the old wives' tale. Your baby needs lots and lots of calcium, so you need to provide this essential mineral during your pregnancy. The Mayo Clinic recommends 1,000 mg a day for pregnant adult women. Milk, fortified orange juice, fortified cereal, yogurt, cheese and spinach are all high in calcium.

Make your diet fun by varying your meals and adding fun foods like fresh berries and peaches, sunflower seeds and almonds. Just remember that your nutrition during pregnancy is an excellent predictor of how healthy your baby will be at birth and beyond.