No strong evidence linking vitamin D levels and preeclampsia

Vitamin D status does not appear to have any effect on the risk of gestational hypertension or preeclampsia, regardless of a woman’s genetic risk profile for vitamin D deficiency.

Writing in the June 21 online edition of the BMJ, researchers reported the results of one- and two-sample mendelian randomization analyses of two pregnancy cohort studies and two case-control studies.

Overall, 7,389 women were included in the one-sample mendelian randomization analysis – 751 with gestational hypertension and 135 with preeclampsia. The two-sample analysis included 3,388 women with preeclampsia and 6,059 controls.

In a conventional multivariable analysis, researchers saw a 3% increase in the relative risk of preeclampsia for each 10% decrease in 25-hydroxyvitamin D levels. However, there was a doubling of risk in women whose 25-hydroxyvitamin D levels were below 25 nmol/L, compared with those with levels at or above 75 nmol/L, but no effect seen for gestational hypertension.

However, in the one-sample mendelian randomization analysis – using genetic risk score as an instrument – the authors saw no clear sign of a linear relationship between 25-hydroxyvitamin D levels and the risk of gestational hypertension or preeclampsia.

The two-sample mendelian randomization analysis showed an odds ratio for preeclampsia of 0.98 per 10% decrease in 25-hydroxyvitamin D level.

“We explored the association between the genetic instruments and intake of vitamin D supplements because, if women with lower genetically predicted 25-hydroxyvitamin D levels are more likely to take supplements, this could theoretically distort our findings,” wrote Maria C. Magnus, PhD, of the Medical Research Council Integrative Epidemiology Unit at the University of Bristol (England) and her coauthors.

They noted that the proportion of women taking vitamin D supplements during pregnancy differed between the two cohorts, which may have reflected cultural, socioeconomic, or policy difference.

The U.S. Institute of Medicine currently recommends that pregnant and lactating women have a dietary intake of 600 IU (15 mcg) of vitamin D per day.

While this study found no strong evidence to support a causal effect of vitamin D status on the risk of gestational hypertension or preeclampsia, the study’s authors suggested similar studies with larger numbers of women with preeclampsia were still needed to definitely establish this.

The study was supported by the European Union and the Research Council of Norway. One author declared funding from the pharmaceutical industry for unrelated research, and several authors declared funding from other institutions. No conflicts of interest were declared.

SOURCE: Magnus MC et al. BMJ. 2018 Jun 21. doi: 10.1136/bmj.k2167.

Vitamin D status does not appear to have any effect on the risk of gestational hypertension or preeclampsia, regardless of a woman’s genetic risk profile for vitamin D deficiency.

Writing in the June 21 online edition of the BMJ, researchers reported the results of one- and two-sample mendelian randomization analyses of two pregnancy cohort studies and two case-control studies.

Overall, 7,389 women were included in the one-sample mendelian randomization analysis – 751 with gestational hypertension and 135 with preeclampsia. The two-sample analysis included 3,388 women with preeclampsia and 6,059 controls.

In a conventional multivariable analysis, researchers saw a 3% increase in the relative risk of preeclampsia for each 10% decrease in 25-hydroxyvitamin D levels. However, there was a doubling of risk in women whose 25-hydroxyvitamin D levels were below 25 nmol/L, compared with those with levels at or above 75 nmol/L, but no effect seen for gestational hypertension.

However, in the one-sample mendelian randomization analysis – using genetic risk score as an instrument – the authors saw no clear sign of a linear relationship between 25-hydroxyvitamin D levels and the risk of gestational hypertension or preeclampsia.

The two-sample mendelian randomization analysis showed an odds ratio for preeclampsia of 0.98 per 10% decrease in 25-hydroxyvitamin D level.

“We explored the association between the genetic instruments and intake of vitamin D supplements because, if women with lower genetically predicted 25-hydroxyvitamin D levels are more likely to take supplements, this could theoretically distort our findings,” wrote Maria C. Magnus, PhD, of the Medical Research Council Integrative Epidemiology Unit at the University of Bristol (England) and her coauthors.

They noted that the proportion of women taking vitamin D supplements during pregnancy differed between the two cohorts, which may have reflected cultural, socioeconomic, or policy difference.

The U.S. Institute of Medicine currently recommends that pregnant and lactating women have a dietary intake of 600 IU (15 mcg) of vitamin D per day.

While this study found no strong evidence to support a causal effect of vitamin D status on the risk of gestational hypertension or preeclampsia, the study’s authors suggested similar studies with larger numbers of women with preeclampsia were still needed to definitely establish this.

The study was supported by the European Union and the Research Council of Norway. One author declared funding from the pharmaceutical industry for unrelated research, and several authors declared funding from other institutions. No conflicts of interest were declared.

SOURCE: Magnus MC et al. BMJ. 2018 Jun 21. doi: 10.1136/bmj.k2167.

Vitamin D status does not appear to have any effect on the risk of gestational hypertension or preeclampsia, regardless of a woman’s genetic risk profile for vitamin D deficiency.

Writing in the June 21 online edition of the BMJ, researchers reported the results of one- and two-sample mendelian randomization analyses of two pregnancy cohort studies and two case-control studies.

Overall, 7,389 women were included in the one-sample mendelian randomization analysis – 751 with gestational hypertension and 135 with preeclampsia. The two-sample analysis included 3,388 women with preeclampsia and 6,059 controls.

In a conventional multivariable analysis, researchers saw a 3% increase in the relative risk of preeclampsia for each 10% decrease in 25-hydroxyvitamin D levels. However, there was a doubling of risk in women whose 25-hydroxyvitamin D levels were below 25 nmol/L, compared with those with levels at or above 75 nmol/L, but no effect seen for gestational hypertension.

However, in the one-sample mendelian randomization analysis – using genetic risk score as an instrument – the authors saw no clear sign of a linear relationship between 25-hydroxyvitamin D levels and the risk of gestational hypertension or preeclampsia.

The two-sample mendelian randomization analysis showed an odds ratio for preeclampsia of 0.98 per 10% decrease in 25-hydroxyvitamin D level.

“We explored the association between the genetic instruments and intake of vitamin D supplements because, if women with lower genetically predicted 25-hydroxyvitamin D levels are more likely to take supplements, this could theoretically distort our findings,” wrote Maria C. Magnus, PhD, of the Medical Research Council Integrative Epidemiology Unit at the University of Bristol (England) and her coauthors.

They noted that the proportion of women taking vitamin D supplements during pregnancy differed between the two cohorts, which may have reflected cultural, socioeconomic, or policy difference.

The U.S. Institute of Medicine currently recommends that pregnant and lactating women have a dietary intake of 600 IU (15 mcg) of vitamin D per day.

While this study found no strong evidence to support a causal effect of vitamin D status on the risk of gestational hypertension or preeclampsia, the study’s authors suggested similar studies with larger numbers of women with preeclampsia were still needed to definitely establish this.

The study was supported by the European Union and the Research Council of Norway. One author declared funding from the pharmaceutical industry for unrelated research, and several authors declared funding from other institutions. No conflicts of interest were declared.

SOURCE: Magnus MC et al. BMJ. 2018 Jun 21. doi: 10.1136/bmj.k2167.