Vitamin D and Pregnancy
By Jeffrey M Wentworth, MD
Appropriate nutrition in pregnancy is vital and vitamin D plays one of these crucial roles within our body. We now realize how important normal vitamin D levels are for good health. Most people are aware of vitamin D’s association with absorption of Calcium for strong bones, but appropriate vitamin D levels can also help prevent both breast and colorectal cancer, type 2 diabetes, some autoimmune diseases and even depression.
Many women have low vitamin D levels because of inadequate exposure to sunlight, increased use of sunscreen and low intake of vitamin D containing foods. Women who are pregnant require even more! A typical prenatal vitamin has only 400 IU of D, this probably is not enough.
The benefits of adequate vitamin D levels in pregnancy are numerous. Mom’s vitamin D status reflects babies vitamin D status, meaning if mom is low…. baby is low. Low vitamin D in pregnancy has been associated with low bone mass for baby (this can lead to rickets which is when a baby has soft and weak bones), increased risk of gestational diabetes, high blood pressure during pregnancy, preeclampsia and an increase risk of childhood asthma.
First-time mothers-to-be with vitamin D deficiency may be up to 4 times more likely to need a Cesarean section! This risk alone is normally enough motivation for most women to “take their D seriously”.
It is difficult for most women to get enough vitamin D from diet alone because only wild-caught fatty fish (salmon, sardines and mackerel) are a good source. I constantly hear “well I drink milk”. That’s great, but milk is fortified with only about 100 IU per cup.
There is no consensus on how much vitamin D a pregnant women requires each day and ultimately it depends on several factors to include initial level, time of year, diet and how far south one lives. The National Institutes of Health recently funded a study that looked at 4000 IU per day in pregnant women and showed this was safe and effective in achieving normal vitamin D levels as well as resulting in fewer pregnancy complications.
Within our practice, we routinely check vitamin D levels at the initial prenatal visit and again at 28 weeks. Replacement recommendations are individualized for each patient depending on the factors above as well as dose and form of vitamin D required.