“Consequences of vitamin D deficiency in pregnancy”


Vitamin D is an essential vitamin for humans. There are two forms of vitamin D that are important in humans, vitamin D2, which is made by plants and vitamin D3 made by animal skin when exposed to sunlight. Therefore, vitamin D can be found in many foods including dairy products, eggs, fish, and cod liver oil.The major role of vitamin D is to maintain normal blood levels of calcium and phosphorus. Through facilitating calcium absorption it has an important role in forming and maintaining strong bones. Severe vitamin D deficiency can lead to rickets, a disease with soft and weak bones in children, osteomalacia that causes weak bones and muscles, and osteoporosis in adults. Recent studies showed increasing evidence regarding the potential protective effects of vitamin D against cardiovascular diseases, high blood pressure, and cancer. Moreover, poor vitamin D status has been associated with several adverse outcomes during pregnancy affecting both the mother and the newborn. Previous studies showed that pregnant women who had lower levels of vitamin D might have higher risk of having gestational diabetes – diabetes occurring during pregnancy –, higher risk of having vaginal bacterial infection, higher risk of preterm delivery (delivery before 37 weeks of gestational age), and higher risk of having cesarean section. The insufficient vitamin D status of the mothers may also affect the fetal growth resulting in lower birth weight, length, and head-circumference.

In the INMA Project the investigators aimed to examine the levels of maternal vitamin D and its potential effects on mothers, the pregnancy, and newborns. They recruited and involved 2,358 mother and child pairs form four regions in Spain including Valencia, Sabadell, Asturias, and Gipuzkoa as a part of the Infancia and Medio Ambiante (INMA) Study. The level of circulating 25(OH)D3, the best measure of vitamin D status in humans, was measured at the end of the first trimester. They collected information regarding diabetes occurring during pregnancy, the time and mode of delivery, and the weight, length, and head circumference of the newborn at delivery.

In the INMA study, including more than 2300 mother-child pairs, the investigators found that women who had sufficient vitamin D levels during pregnancy had lower risk of having cesarean section because of obstructed labor. Nevertheless, they did not find any evidence of an association between lower level of vitamin D and gestational diabetes, preterm delivery, and lower body metrics of the newborn. However, the study showed that more than 30{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} of the participants had insufficient levels of vitamin D, and about 20{3effe4377b6f02be2524d084f7d03914ac32a2b62c0a056ca3444e58c1f10d0b} of the participants had vitamin D deficiency.

Although the investigators did not find strong evidence of an association between lower vitamin D levels and adverse outcomes of pregnancy, Dr. Rodriguez the primary investigator of the study, highlights the importance of a balanced diet during pregnancy and including sufficient vitamin D consumption. Results from other studies suggest that sufficient vitamin D levels could play an important role in fetal growth and development.

Reference: Rodriguez A, García-Esteban R, Basterretxea M, Lertxundi A, Rodríguez-Bernal C, Iñiguez C, Rodriguez-Dehli C, Tardón A, Espada M, Sunyer J, Morales E. Associations of maternal circulating 25-hydroxyvitamin D3 concentration with pregnancy and birth outcomes. BJOG. 2014 Sep 11. doi: 10.1111/1471-0528.13074. [Epub ahead of print]