4. Discussion
obesity, depression, hypertension
OBESITY, PRE-ECLAMPSIA, GESTATIONAL DIABETES, ADVERSE EVENTS, EARLY PREGNANCY, ADVERSE EFFECTS, SECONDARY, MISCARRIAGES, VITAMIN D DEFICIENCY, PRETERM DELIVERY, HYPERTENSION
In pregnant women with OW/OB, administering 800 IU of oral vitamin D3 supplement from early pregnancy significantly increased serum 25OHD levels and the proportion of women achieving sufficient 25OHD compared to the control group receiving 400 IU of vitamin D3 supplement at 24–28 weeks gestation. This higher supplementation dose effectively prevented vitamin D deficiency, as indicated by serum 25OHD < 25 nmol/L in this population. However, the additional 400 IU of vitamin D3 in the intervention had no discernible impact on lipid profiles and glycaemic measures, although a marginal effect on improving foetal growth was observed specifically in women who complied with the intervention or those with obesity.Our findings are aligned with a randomised clinical trial involving pregnant women with OW/OB, which reported a significant difference of 8.7 nmol/L and 10.3 nmol/L in 25OHD levels between groups receiving 400 IU/day and 800 IU/day of supplementation, respectively, in women with OW/OB [The impact of vitamin D3 supplementation on lipid metabolism during pregnancy remains a complex and debated topic. Despite the known role of vitamin D in reducing liver triglyceride synthesis and cholesterol conversion to bile acids [Vitamin D is crucial for maintaining optimal maternal and foetal health during pregnancy. Numerous studies have demonstrated that low 25OHD levels are associated with adverse effects on maternal health, including an elevated risk of gestational diabetes, pre-eclampsia, caesarean section, preterm delivery, miscarriages, and postpartum depression [Taken together, our study showed that over three-quarters of pregnant women with OW/OB had serum 25OHD levels below 50 nmol/L in early pregnancy. Consuming a daily dose of 800 IU of vitamin D3 supplementation effectively increased the proportion of women achieving sufficient 25OHD levels, surpassing 50 nmol/L in late-mid pregnancy, with no adverse events directly related to the supplementation reported. Given the high prevalence of vitamin D insufficiency in our population of pregnant women with OW/OB, implementing universal supplementation with a minimum dose of 800 IU/day of vitamin D3 may be cost-effective [Our study stands out as one of the rare randomised controlled trials investigating the effects of oral vitamin D3 supplementation on serum 25OHD and metabolic biomarkers specifically in pregnant women with OW/OB. These findings offer crucial insights into the appropriate vitamin D supplementation doses needed for this population, particularly in an Asian context. The early initiation and sustained administration of vitamin D3 supplementation until delivery, along with high participant compliance, enhanced the reliability of our findings. However, our study faced limitations in adequately powering the analysis of secondary outcomes, warranting a specifically designed and powered study focused on maternal and birth outcomes in response to varied vitamin D3 supplementation dosages. Moreover, we did not explore the use of higher supplementation doses that have shown significant effects in other studies. While the study excluded individuals using lipid-lowering medications and those with chronic hypertension taking antihypertensive drugs, individuals taking other medications like benzodiazepines, antidepressants, and proton pump inhibitors, which have been shown to affect vitamin D status, were not excluded [Moreover, there are some limitations in the generalisability of our findings. While our study offers a distinctive perspective on vitamin D deficiency in the Asian context, our unique geographical location and ethnic composition may restrict the broader application of our study’s findings. Situated just 1° north of the equator, Singapore has a tropical rainforest climate characterised by the absence of distinct seasons. This results in no seasonal variation in UV exposure, which is not observed in many other countries [