There are eight B vitamins, often referred to as B-complex vitamins. These important nutrients help the body convert food into energy, in addition to performing other important functions such as aiding in the formation of red blood cells. It is vital for pregnant women to receive adequate nutrition, and B-complex vitamins, in particular, are important for the proper growth and development of unborn babies.
B-1 and B-2
Thiamine, also known as vitamin B-1, is vital for the brain development of babies, and it aids in the normal function of the muscles, nervous system and heart, according to the BabyCenter website. Pregnant women require about 1.4 milligrams of thiamine per day. Riboflavin, sometimes referred to as vitamin B-2, is important for healthy skin, growth and good vision. Thiamine is also vital to the muscle, nerve and bone development of babies. The recommended dosage of riboflavin is 1.4 milligrams per day for pregnant women.
B-3 and B-5
Niacin, also known as vitamin B-3, helps produce sex-related hormones, and it's important for circulation. Pregnant women have an increased requirement for niacin, with a recommended daily allowance of 18 milligrams. Pantothenic acid, or vitamin B-5, is a necessary nutrient in the production of hormones and cholesterol. It is also required to metabolize carbohydrates, fats and proteins. Pregnant women require 6 milligrams of pantothenic acid per day.
B-6 and B-7
Pyridoxine, more commonly known as vitamin B-6, helps the body make several neurotransmitters, and it is required for the normal development and function of the brain. Pyridoxine may be especially useful for pregnant women, as some research has shown that a daily dose of 30 milligrams can help reduce morning sickness, according to University of Maryland Medical Center. Biotin, or vitamin B-7, is often used to treat hair loss, brittle nails and skin rash in infants. According to MedlinePlus, pregnant women can become deficient in biotin. Pregnant women should consume 30 micrograms of biotin per day.
B-9 and B-12
Of all the B-complex vitamins, folic acid, also known as vitamin B-9, plays the most important role in pregnant women. When folic acid is deficient, birth defects can occur, even as early as the first few weeks of pregnancy. To prevent any deficiencies, all women, whether they are trying to get pregnant or not, should be sure to consume 400 micrograms of folic acid each day, according to the Centers for Disease Control and Prevention. Vitamin B-12, which is required for DNA synthesis and proper red blood cell formation, crosses the placenta during pregnancy. Because B-12 is present in very few vegan food sources, the American Dietetic Association recommends supplemental vitamin B-12 for pregnant women who are vegans. For pregnant women, the recommended dietary allowance of vitamin B-12 is 2.6 micrograms.
It is important to remember that all B-complex vitamins are water-soluble, meaning they must be consumed each day because the body cannot store them. Good sources of B vitamins include proteins, such as fish, eggs, meat, poultry and dairy products, as well as leafy green vegetables and legumes. For pregnant women who may lack B-complex vitamins in the diet, supplemental B-complex vitamins, which include all of the B vitamins, can be purchased.