The high blood pressure condition preeclampsia can lead to strokes and organ failure. It is a major cause of illness and death for pregnant women, and also is associated with a greater risk of stillbirth and preterm birth. Researchers have estimated that preeclampsia occurs in 2-8% of pregnancies worldwide and its a growing issue.
Studies have suggested that maternal preeclampsia may increase the risk of high blood pressure for their children. Vitamin D deficiency has been associated with an increased risk of cardiovascular diseases including preeclampsia.
Vitamin D also plays a role in fetal development and higher early-life vitamin D levels may be protective against childhood high BP. However, no study has examined whether the inter-generational association of preeclampsia with childhood and adolescent BP varies by vitamin D status.
Researchers at Johns Hopkins Bloomberg School of Public Health, US, wanted to know if vitamin D levels in the womb would modify this association between maternal preeclampsia and hypertension in childhood.
To investigate this question, the team analysed data that had been gathered on 754 mother-child pairs from 1998 to 2018 in a large epidemiological study conducted at the Boston Medical Center in Massachusetts. The dataset included information on preeclampsia during pregnancy, tests on blood from the umbilical cord at birth, and the children's blood pressure from age 3 to 18.
Their findings suggest that higher vitamin D levels in pregnancy may help protect children born to preeclamptic women from developing high blood pressure.
Roughly 10% of the women in the study group had preeclampsia, and the analysis revealed that their children on average had higher systolic blood pressure than the children born to non-preeclamptic mothers - about 5 percentile points higher, when all the blood pressure readings were arranged on a 0 to 100 percentile scale.
Cord-blood vitamin D levels clearly modified these associations, and in a dose-related manner. Children in the lowest 25 percent range of vitamin D levels (lowest "quartile") were about 11 percentile points higher in blood pressure, on average, if their mothers had had preeclampsia, compared to children of non-preeclamptic mothers.
For children in the highest vitamin D quartile, there appeared to be no difference in average blood pressure if their mothers had had preeclampsia - in other words, the results suggest that having relatively high vitamin D levels at birth, which could be achieved through dietary supplements, may completely mitigate the risk brought by preeclampsia.
Study senior author Noel Mueller, PhD, an assistant professor in the Department of Epidemiology at the Bloomberg School, said: "There is increasing evidence that cardiovascular disease risk is, to a great extent, programmed in the womb, and we now see that it may be vitamin D that alters this programming in a beneficial fashion."
Vitamin D and cardiovascular health
Vitamin D may be associated with cardiovascular health and cardiovascular physiology and pathology through multiple pathways, which include regulations of myocyte proliferation and hypertrophy and the renin-angiotensin system. Vitamin D also may be a factor in implantation, placentation, and angiogenesis processes and is essential for maintaining a healthy pregnancy.
Mechanisms on how vitamin D may modify the association between preeclampsia and child BP, however, is unclear. The current findings need to be replicated in other observational studies. whether replicated, this benefit also needs to be confirmed in future clinical trials of vitamin D supplementation in pregnancies with preeclampsia with long term follow-up of their children. This cautious interpretation of the current findings owes to the inconclusive findings of randomised clinical trials examining how vitamin D supplementation may reduce adult BP.
"If other epidemiological studies confirm these findings, then randomised trials would be needed to determine conclusively if higher vitamin D in mothers at risk of preeclampsia protects against childhood high blood pressure," Mueller says.
Source: JAMA Network Open
Mingyu Zhang, Erin D. Michos, Guoying Wang, Xiaobin Wang, Noel T. Mueller.
"Associations of Cord Blood Vitamin D and Preeclampsia With Offspring Blood Pressure in Childhood and Adolescence"