Vitamin D and the risk of dystocia: A case-control study

Predictive value of Vitamin D levels in pregnant women on gestational length and neonatal weight in China: a population-based retrospective study

BACKGROUND

Vitamin D deficiency, a common occurrence among pregnant women, is an emerging public health concern worldwide. According to research, prenatal vitamin D deficiency is associated with various complications. This study assessed the vitamin D status of pregnant women in Yanbian, Jilin Province, as well as the correlation and predictive value of their vitamin D levels in relation to gestational length (weeks) and fetal weight, aiming to provide a basis for clinical diagnosis and treatment.

METHODS

We conducted a population-based retrospective study involving 510 pregnant women from August 2019 to October 2022. Blood samples were collected at 16-20 weeks of gestation for the detection of serum vitamin D levels. Statistical analyses were performed using SPSS 28.0 and R 4.1.0 software. Multifactorial logistic regression analysis was employed to establish whether each variable was a risk factor for deliveries at ≤ 38 gestational weeks and low fetal weight. These results were used to construct a risk prediction model, and the model's predictive efficacy was evaluated. Results or differences with p < 0.05 were considered statistically significant.

RESULTS

Multifactorial logistic regression analysis revealed that vitamin D ≤ 14.7 ng/mL(OR: 1.611; 95% CI: 1.120-2.318; P = 0.010), Bone Mineral Density (BMD) T-value ≤-1(OR: 1.540; 95%CI: 1.067-2.223; P = 0.021), and gestational hypertension(OR: 7.173; 95% CI: 1.482-34.724; P = 0.014) were the independent risk factors for deliveries at ≤ 38 gestational weeks. Additionally, vitamin D ≤ 14.7 ng/mL(OR: 1.610; 95%CI: 1.123-2.307; P = 0.009), BMD T-value ≤ -1(OR: 1.560; 95%CI: 1.085-2.243; P = 0.016), and gestational hypertension(OR: 4.262; 95% CI: 1.058-17.167; P = 0.041) were the independent risk factors for low fetal weight (< 3400 g).

CONCLUSION

This study revealed that low vitamin D levels are an independent risk factor for a short gestational length and low fetal weight. Prenatal low BMD T-value and comorbid hypertensive disorders were also found to increase the risk of a short gestational length and low fetal weight.

Higher Plasma Myo-Inositol in Pregnancy Associated with Reduced Postpartum Blood Loss: Secondary Analyses of the NiPPeR Trial

We previously reported that a combined myo-inositol, probiotics, and enriched micronutrient supplement (intervention) taken preconception and in pregnancy reduced postpartum blood loss (PBL) and major postpartum hemorrhage compared with a standard micronutrient supplement (control), as secondary outcomes of the NiPPeR trial. This study aimed to identify the intervention components that may contribute to this effect. Associations of plasma concentrations of myo-inositol and vitamins B2, B6, B12, and D at preconception (before and after supplementation), early (~7-weeks), and late pregnancy (~28-weeks) with PBL were assessed by multiple linear regression, adjusting for site, ethnicity, preconception BMI, parity, and previous cesarean section. Amongst 583 women, a higher concentration of myo-inositol in early pregnancy was associated with a PBL reduction [βadj -1.26 (95%CI -2.23, -0.29) mL per µmol/L myo-inositol increase, p = 0.011]. Applying this co-efficient to the increase in mean 7-week-myo-inositol concentration of 23.4 µmol/L with the intervention equated to a PBL reduction of 29.5 mL (~8.4% of mean PBL of 350 mL among controls), accounting for 84.3% of the previously reported intervention effect of 35 mL. None of the examined vitamins were associated with PBL. Therefore, myo-inositol may be a key intervention component mediating the PBL reduction. Further work is required to determine the mechanisms involved.

Mediation Effect of Social Distancing on Neonatal Vitamin D Status and Related Clinical Outcomes during the Coronavirus Disease-19 Pandemic

BACKGROUND

We analyzed the impact of social distancing (SD) on vitamin D status and associated morbidity in neonates during the coronavirus disease (COVID-19) pandemic.

METHODS

Serum levels of 25-hydroxy vitamin D (25OHD) and clinical characteristics of newborn infants before (2019) and during SD (2021) were compared.

RESULTS

A total of 526 neonates (263 in 2019 and 263 in 2021) were included. The rate of vitamin D deficiency in neonates (47.1% vs. 35.4 %, p = 0.008) decreased and the rate of maternal vitamin D intake increased (6.8% vs. 37.6%, p < 0.001), respectively, during SD compared to those in 2019. The rates of hypocalcemia (12.5% vs. 3.8%, p < 0.001) and respiratory illness (57.0% vs. 43.0%, p = 0.002) decreased during SD. Neonatal vitamin D deficiency during SD was associated with maternal vitamin D supplementation (odds ratio [OR] = 0.463, p = 0.003) but was not associated with SD (OR = 0.772, p = 0.189). The mediation effect of SD on neonatal morbidity by neonatal vitamin D status was statistically insignificant.

CONCLUSIONS

SD might affect the increased maternal vitamin D intake and decreased neonatal vitamin D deficiency. However, neonatal morbidity was not affected by SD, even with neonatal vitamin D status changes.

The association between maternal vitamin D deficiency and postpartum hemorrhage and uterine atony

INTRODUCTION

Postpartum hemorrhage is the leading cause of maternal morbidity and mortality worldwide. There are several known risk factors for postpartum hemorrhage related to pregnancy and delivery, but less evidence of predisposing factors. Recent research has shown that vitamin D deficiency may increase the risk of cesarean section due to dystocia, based on its effect on striated muscle as well as possible effect on the myometrium. Whether vitamin D deficiency increases the risk for postpartum hemorrhage and especially atonic hemorrhage is unknown.

MATERIAL AND METHODS

This was a retrospective translational study. The study population included 1367 women in Sweden and the main exposure was the serum concentration of 25-hydroxylated vitamin D at time of delivery. The LIASON® 25 OH vitamin D total assay method was used for analyzing 25-hydroxylated vitamin D. Vitamin D insufficiency was defined as serum concentration <50 nmol/L and vitamin D deficiency as serum concentrations <25 nmol/L. Primary outcomes were postpartum hemorrhage and severe postpartum hemorrhage defined as bleeding ≥500 mL and ≥ 1000 mL, respectively 2 h after delivery. Secondary outcome was atonic postpartum hemorrhage. Crude and adjusted odds ratios were calculated with 95% confidence intervals using univariable and multivariable logistic regression. Three different adjustment methods were used, adjusting for maternal, obstetrical and neonatal confounders.

RESULTS

Postpartum hemorrhage and severe postpartum hemorrhage afflicted 31.3% and 6.4% of the women, respectively. Rate of atonic postpartum hemorrhage was 21% in the whole population. Rate of vitamin D insufficiency and deficiency was 57%. Vitamin D insufficiency or deficiency was neither found to be associated with postpartum hemorrhage, nor with atonic postpartum hemorrhage.

CONCLUSIONS

In this study, the vitamin D status of women at the time of delivery was not a predictor of postpartum hemorrhage overall or atonic postpartum hemorrhage.

Does antenatal cholecalciferol supplementation affect the mode or timing of delivery? Post hoc analyses of the MAVIDOS randomized controlled trial

BACKGROUND

Observational studies relating maternal 25-hydroxyvitamin D status to timing and mode of delivery have reported inconsistent results. We assessed the effect of antenatal cholecalciferol supplementation on the incidence of preterm birth, delivery mode and post-partum haemorrhage (PPH).

METHODS

MAVIDOS was a randomized, double-blind, placebo-controlled trial of 1000 IU/day cholecalciferol from 14 weeks' gestation until delivery. Gestational age, mode of delivery [categorized as spontaneous vaginal delivery (SVD), instrumental (including forceps and vacuum extraction) or Caesarean section] and PPH (>500 ml estimated blood loss) were determined from medical records.

RESULTS

A total of 965 women participated in the study until delivery. Gestation at birth and incidence of preterm birth (cholecalciferol 5.7%, placebo 4.5%, P = 0.43) were similar between the two treatment groups. SVD (versus instrumental or Caesarean delivery) was more likely in women randomized to cholecalciferol [Relative Risk (RR) 1.13, 95% confidence interval (CI) 1.02,1.25] due to lower instrumental (RR 0.68, 95%CI 0.51,0.91) but similar risk of Caesarean delivery (RR 0.94, 95%CI 0.74,1.19). PPH was less common in women randomized to cholecalciferol [32.1% compared with placebo (38.1%, P = 0.054) overall], but similar when stratified by delivery mode.

CONCLUSIONS

Antenatal cholecalciferol supplementation did not alter timing of birth or prevalence of preterm birth but demonstrated a possible effect on the likelihood of SVD.

Mode of delivery and maternal vitamin D deficiency: an optimized intelligent Bayesian network algorithm analysis of a stratified randomized controlled field trial

This study aimed to elucidate the algorithm of various influential factors relating to the association between 25-hydroxyvitamin D (25(OH)D) concentration at delivery and mode of delivery. The investigation constituted a secondary analysis using data collected as part of the Khuzestan Vitamin D Deficiency Screening Program in Pregnancy, which is a stratified randomized vitamin D supplementation-controlled trial comprising 1649 eligible pregnant women. The Bayesian Network (BN) method was utilized to determine the association algorithm between diverse influential factors associated with maternal vitamin D and mode of delivery. The optimized intelligent BN algorithm revealed that women presenting with moderate (35.67%; 95% CI: 33.36-37.96) and severe vitamin D deficiency (47.22%; 95% CI: 44.81-49.63) at delivery were more likely to undergo cesarean section than those presenting with normal concentrations of this nutritional hormone (18.62%; 95% CI: 16.74-20.5). The occurrence probabilities of preeclampsia in mothers with normal, moderate, and severe vitamin D deficiency at delivery were (1.5%; 95% CI: 0.92-2.09), (14.01%; 95% CI: 12.33-15.68), and (26.81%; 95% CI: 24.67-28.95), respectively. Additionally, mothers with moderate (11.81%; 95% CI: 10.25-13.36) and severe (27.86%; 95% CI: 25.69-30.02) vitamin D deficiency exhibited a higher probability of preterm delivery in comparison to those presenting with normal concentrations (1.12%; 95% CI: 0.62-1.63). This study demonstrated that the vitamin D status of pregnant women at delivery could directly affect the mode of delivery and indirectly through maternal complications, such as preeclampsia and preterm delivery, leading to a higher occurrence probability of cesarean section.

Peripartum outcomes after combined myo-inositol, probiotics, and micronutrient supplementation from preconception: the NiPPeR randomized controlled trial

BACKGROUND

Evidence that nutritional supplementation before and during pregnancy improves peripartum outcomes is sparse. In the Nutritional Intervention Preconception and During Pregnancy to Maintain Healthy Glucose Metabolism and Offspring Health (NiPPeR) trial, we previously reported that a combined myo-inositol, probiotics, and micronutrient supplement started at preconception showed no difference in the primary outcome of gestational glycemia, but did reduce the risk of preterm delivery, preterm prelabor rupture of membranes, and major postpartum hemorrhage.

OBJECTIVE

This study aimed to examine the hypothesis that a reduction in major postpartum hemorrhage following a combined nutritional (myo-inositol, probiotics, and micronutrients) intervention is linked with promotion of labor progress and reduced operative delivery.

STUDY DESIGN

This double-blind randomized controlled trial recruited 1729 women from the United Kingdom, Singapore, and New Zealand, aged 18 to 38 years, and planning conception between 2015 and 2017. The effects of the nutritional intervention compared with those of a standard micronutrient supplement (control), taken at preconception and throughout pregnancy, were examined for the secondary outcomes of peripartum events using multinomial, Poisson, and linear regression adjusting for site, ethnicity, and important covariates.

RESULTS

Of the women who conceived and progressed beyond 24 weeks' gestation with a singleton pregnancy (n=589), 583 (99%) provided peripartum data. Between women in the intervention (n=293) and control (n=290) groups, there were no differences in rates of labor induction, oxytocin augmentation during labor, instrumental delivery, perineal trauma, and intrapartum cesarean delivery. Although duration of the first stage of labor was similar, the second-stage duration was 20% shorter in the intervention than in the control group (adjusted mean difference, -12.0 [95% confidence interval, -22.2 to -1.2] minutes; P=.029), accompanied by a reduction in operative delivery for delayed second-stage progress (adjusted risk ratio, 0.61 [0.48-0.95]; P=.022). Estimated blood loss was 10% lower in the intervention than in the control group (adjusted mean difference, -35.0 [-70.0 to -3.5] mL; P=.047), consistent with previous findings of reduced postpartum hemorrhage.

CONCLUSION

Supplementation with a specific combination of myo-inositol, probiotics, and micronutrients started at preconception and continued in pregnancy reduced the duration of the second stage of labor, the risk of operative delivery for delay in the second stage, and blood loss at delivery.

Maternal plasma levels of vitamin D in postterm pregnancy

This study was conducted to examine the levels of vitamin D in postterm pregnancy. The study consisted of two groups: Group 1: women with postterm pregnancy in whom labour has not started (n = 40). Group 2: pregnant women with spontaneous labour between 37 and 41 weeks of gestation (n = 40). Demographic characteristics of individuals, age, body mass index, gravida, parity, living child, number of abortions and birth characteristics were recorded. Prepartum and postpartum haemoglobin (Hb) and haematocrit (Hct) values ​​and vitamin D levels of pregnant women were measured. We found no significant differences in vitamin D levels, smoking, mode of delivery, induction of labour, methods of cervical ripening and maternal and perinatal complications between the groups (p > .05). D vitamin in the model had a statistically significant effect on prepartum Hb (p < .05). Vitamin D levels seem not to be associated with postterm pregnancy. Vitamin D had a statistically significant effect on prepartum Hb.IMPACT STATEMENTWhat is already known on this subject? The aetiology of post term pregnancy is not clearly known, factors such as foetal anencephaly, foetal sex, placental sulfatase deficiency, genetic factors, and high pre-pregnancy body mass index play a role.What do the results of this study add? Vitamin D levels seem not to be associated with postterm pregnancy. Vitamin D had a statistically significant effect on prepartum Hb.What are the implications of these findings for clinical practice and/or further research? Further studies are needed to clarify the relationship between vitamin D levels and postterm pregnancy.