Most studies into periconceptional folic acid (FA) supplements focus on the effects on fetal development. However, the Chinese researchers behind this tudy recognized a lack of population-based research on the association between using FA during pregnancy and the placenta’s development.
To address this, they investigated the impact of FA supplementation in different pregnancies on placenta-related parameters at delivery in women recruited from Ma’anshan City, Anhui Province in China between May 2013 and September 2014.
Overall, the researchers noted that, “FA use before conception could increase placental width and area, and FA use in early/middle pregnancy could increase placental thickness.”
They called for further studies to confirm the findings.
Inconsistent results
The placenta is a temporary endocrine organ that facilitates gas, nutrient and waste exchange between maternal and fetal compartments. FA deficiency leads to disruption of DNA methylation and normal epigenetic regulation. This can affect placental development and function, lead to changes in fetal programming and increase the risk of some diseases in adulthood.
Several studies have found that FA supplementation is beneficial for the reduction of homocysteine levels. Homocysteine can induce placental endothelial cell damage, affect the growth and development of the placenta and fetus and induce preeclampsia.
Current studies on the effects of FA supplementation on placental development have been inconsistent, however. One survey reported that pregnant women taking 5 mg of FA a day had an 11.9% average increase in placental weight compared to those not taking it. In contrast, some studies have found that FA supplementation is not associated with placental weight.
Placental weight is related to birth weight, therefore when folic acid directly affects placental growth and development, it also indirectly impacts fetal growth.
"Placental weight is just one of the indicators of placental development and cannot fully explain the development of the placenta," the researchers wrote. "This study attempts to comprehensively investigate the effects of FA supplementation in different pregnancies on placental development from multiple dimensions."
Measuring the placenta
The study collected data on FA use from one month before conception to delivery. Participants were recruited at their first antenatal care visit at Ma’anshan Maternal and Child Health Care Center. In total, 2,708 were included in the final analysis.
To assess use of FA supplements in different periods, all participants were asked to complete a questionnaire at their routine obstetric visit. It covered the date supplement use began, frequency of use (times/week), dose and supplement brand.
Data on placental size and shape were measured after birth within half an hour by trained personnel. First, the placenta was expanded on a flat surface. Then the longest length of the placental surface was measured along with the maximal diameter using a transparent plastic ruler. Placental thickness was measured at the thickest point.
Based on multiple regression analysis, researchers used propensity score weighting to enhance comparability between different FA supplementation groups.
Increased width, area and thickness
The researchers noted that when comparing supplemented and non-supplemented groups, FA supplementation before conception was associated with increased placental width and surface area. They also found that FA use in early/middle pregnancy was related to increased placental thickness.
“In conclusion, our study provided evidence that FA supplementation at different stages of pregnancy had a potential impact on placental development,” they wrote, speculating that the results are due to the fact that periconception folic acid supplementation may cause epigenetic modifications in the preimplantation embryo, which may then result in increased placental and fetal growth patterns.
As limitation, the studynoted that the lack of dietary information prevented them from evaluating the effect of dietary folate. The limited data from similar studies was also cited as constraint, and potential interactions among multiple vitamins were not taken into account.
Source: Nutrients
doi: 10.3390/nu16111729
"Placenta-Related Parameters at Delivery in Relation to Folic Acid Supplementation in Different Pregnancies"
Authors: Yating Ren et al.