Vitamin D supplementation in pregnancy-a survey of compliance with recommendations

Association of vitamin D intake during pregnancy with small vulnerable newborns: a population-based cohort study

Maternal vitamin D deficiency is common worldwide and has a significant impact on newborns. However, whether vitamin D intake during pregnancy is related to small vulnerable newborns (SVN) has not been confirmed. Thus, we sought to examine the relationship between maternal vitamin D intake, including vitamin D supplementation and dietary intake, and the risk of SVN. A total of 2980 Chinese mother-infant pairs were included in this study. Information on vitamin D supplementation and dietary intake was prospectively collected through face-to-face interviews. The outcomes assessed included low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), and SVN (having LBW, PTB, or SGA). Logistic regression models were used to evaluate the association of vitamin D intake with different types of SVN, and a restricted cubic spline function was modeled to explore their dose-response associations. Compared to the lowest total vitamin D intake in the first trimester, the highest total vitamin D intake was associated with a 50.0% decrease in the SGA risk (OR: 0.50, 95% CI: 0.26, 0.96) and a 41.0% decrease in the SVN risk (OR: 0.59, 95% CI: 0.36, 0.95). Similar protective results were observed between vitamin D supplementation in the first trimester and SGA and SVN risks. Moreover, a significant L-shaped relationship was identified for total vitamin D intake, vitamin D supplementation, and dietary intake with the risk of different types of SVN. In conclusion, higher total vitamin D intake and supplementation in the first trimester were associated with a reduced risk of SGA and SVN.

A Study of Vitamin D Status and Its Influencing Factors among Pregnant Women in Szeged, Hungary: A Secondary Outcome of a Case-Control Study

Adequate vitamin D (VD) intake during pregnancy is needed for fetal development and maternal health maintenance. However, while there is no doubt regarding its importance, there is not a unified recommendation regarding adequate intake. The main aim of our study was to measure the VD serum level of studied women, together with its potential influencing factors: demographic (i.e., age, level of education, relationship status and type of residence), conception and pregnancy related factors. Results are based on secondary data analyses of a retrospective case-control study of 100 preterm and 200 term pregnancies, where case and control groups were analyzed together. Data collection was based on a self-administered questionnaire, health documentation, and maternal serum VD laboratory tests. VD intake was evaluated by diet and dietary supplement consumption. According to our results, 68.1% of women took some kind of prenatal vitamin, and only 25.9% of them knew about its VD content. Only 12.1% of included women reached the optimal, 75 nmol/L serum VD level. Higher maternal serum levels were associated with early pregnancy care visits (p = 0.001), assisted reproductive therapy (p = 0.028) and advice from gynecologists (p = 0.049). A correlation was found between VD intake and serum levels (p < 0.001). Despite the compulsory pregnancy counselling in Hungary, health consciousness, VD intake and serum levels remain below the recommendations. The role of healthcare professionals is crucial during pregnancy regarding micronutrients intake and the appropriate supplementation dose.

Three-stage pattern of rapid increase, plateau, and subsequent decline in vitamin D concentration during pregnancy among Chinese women: a large-scale survey

Background

There is an incomplete understanding of fluctuations in vitamin D (VitD) concentration during pregnancy among Chinese women. Furthermore, previous research has yielded conflicting results in this area. This study aims to investigate the changes in VitD status and deficiency in Chinese pregnant women across various age groups, gestational weeks, and as well as seasonal variations through conducting a large-scale survey.

Methods

A toal of 11,220 Chinese pregnant women between 2021 and April 2023 were included in this study. Generalized additive models (GAM), stratified analysis, and restricted cubic splines (RCS) were used to analyze changes in VitD status and deficiency risk during pregnancy.

Results

Of the participants, 45.2% had deficient concentration of 25-hydroxyvitamin D. VitD concentration and deficiency rate do not show linear changes with age and gestational weeks. With increasing gestational weeks, VitD concentration rapidly increased in women with gestational age < 20 weeks, remained stable between 20 and 30 weeks, and decreased beyond 30 weeks; however, the odds of VitD deficiency showed three different patterns: a rapid decline, a stable period, and a mild increase, respectively. Based on the stratified regression analysis, VitD deficiency odds increased by 16% with each additional week of gestation in pregnant women with gestational age > 30 weeks, OR = 1.16 (1.10-1.22), p < 0.001. Interaction effect analysis indicated that pregnant women over 35 years with gestational weeks between 20 and 30 had the lowest odds of VitD deficiency.

Conclusion

VitD concentration undergo three phases during pregnancy: rapid increase, plateau, and subsequent decrease. VitD deficiency odds was highest in pregnant women under 25 with gestational ages <20 and lowest in pregnant women over 35 with gestational ages between 20 and 30. The odds of deficiency increase slightly in pregnant women with gestational ages beyond 30 weeks, indicating that they may require additional VitD supplementation.

Maternal plasma vitamin D levels across pregnancy are not associated with neonatal birthweight: findings from an Australian cohort study of low-risk pregnant women

BACKGROUND

In utero environments can be highly influential in contributing to the development of offspring obesity. Specifically, vitamin D deficiency during pregnancy is associated with adverse maternal and child health outcomes, however its relationship with offspring obesity remains unclear. We assessed maternal vitamin D status across pregnancy, change in plasma vitamin D concentrations and associations with neonatal birthweight, macrosomia and large for gestational age.

METHODS

Women (n = 221) aged 18-40 years with singleton (low-risk) pregnancies, attending antenatal clinics at a tertiary-level maternity hospital were recruited at 10-20 weeks gestation. Medical history, maternal weight and blood samples at three antenatal clinic visits were assessed; early (15 ± 3 weeks), mid (27 ± 2 weeks) and late (36 ± 1 weeks) gestation. Maternal 25(OH)D was analysed from stored plasma samples via liquid chromatography-tandem mass spectrometry (LC/MS/MS). Neonatal growth parameters were collected at birth. Unadjusted and adjusted linear and logistic regression assessed associations of maternal vitamin D with birthweight, macrosomia and large for gestational age.

RESULTS

Mean plasma 25(OH)D increased from early (83.8 ± 22.6 nmol/L) to mid (96.5 ± 28.9 nmol/L) and late (100.8 ± 30.8 nmol/L) gestation. Overall 98% of women were taking vitamin D-containing supplements throughout their pregnancy. Prevalence of vitamin D deficiency (25(OH)D < 50 nmol/L) was 6.5%, 6.3% and 6.8% at early, mid and late pregnancy respectively. No statistically significant association was found between 25(OH)D or vitamin D deficiency at any timepoint with neonatal birthweight, macrosomia or large for gestational age.

CONCLUSIONS

Prevalence of vitamin D deficiency was low in this cohort of pregnant women and likely related to the high proportion of women taking vitamin D supplements during pregnancy. Maternal 25(OH)D did not impact offspring birth weight or birth size. Future studies in high-risk pregnant populations are needed to further assess maternal vitamin D status and factors in utero which promote early life obesity.

Prevalence of calcium and vitamin D deficiency and their association with feto-maternal outcomes in a sample of Iranian pregnant women

BACKGROUND

Calcium and vitamin D deficiency is common among Iranian women of childbearing age and poses adverse effects on pregnancy outcomes. The aim of the current study was to determine the prevalence of vitamin D and calcium in a sample of Iranian pregnant women and to assess its correlation with the feto-maternal outcomes.

METHODS

In this prospective cross-sectional study, a sample of pregnant women between 15 to 45 years who were in the third trimester were recruited from a number of hospitals in Tehran. Data were collected by the means of a self-developed questionnaire, interviews, physical examination, and paraclinical tests including measuring the serum level of calcium, vitamin D, parathormone (PTH) and phosphorous (Pi). The questionnaire obtained information on age, level of education, socio-economic status, parity, gravidity, calcium intake during pregnancy, as well as feto-maternal outcomes.

RESULTS

We included a total number of 233 singleton pregnancies. Most of the subjects (58.4%) had vitamin D deficiency and 12.0% suffered from severe vitamin D deficiency. Vitamin D deficiency was adversely associated with the years of education (p= 0.007), serum level of parathormone (p< 0.001). The Metabolic Equivalent of Task (MET) (p< 0.001), the exercise sequence per week (p< 0.001), sun exposure (p< 0.001), higher rate of sunscreen usage (p= 0.011) and higher BMI (p= 0.005). Vitamin D deficiency was associated with higher rate of cesarean delivery (p= 0.024), higher rate of diastolic hypertension (p= 0.019), higher rate of neonatal jaundice (p= 0.009) and higher rate of neonatal respiratory infections (p< 0.001). Serum level of PTH was a significant risk factor for severe vitamin D deficiency while calcium D supplementation, MET and sunscreen were significant protective factors.

CONCLUSION

The prevalence of vitamin D deficiency during pregnancy among Iranian women is extremely high and is associated with adverse pregnancy outcomes including cesarean delivery, neonatal jaundice and neonatal respiratory infections. Low vitamin D supplementation and sun exposure, lack of physical activity and high BMI are the etiologies. Increasing the knowledge along with vitamin D supplementation during the pregnancy is recommended in Iranian population.

Determinants of Vitamin D Supplementation among Individuals with Type 1 Diabetes

Half of the individuals with type 1 diabetes (T1DM) may present Vitamin D (VD) deficiency. There is little known about factors determining a decision on VD supplementation. The study aimed to determine the factors affecting vitamin D supplementation in people with T1DM. A cross-sectional survey study using the authors’ questionnaire paper and its digital version was performed. The questions involved data on the basic characteristics of the respondent, medical history, VD supplementation status, influence of the social environment, self-education, and the most important personal motivator for VD supplement use. Multivariate logistic regression analysis was performed. We collected a total of n = 184 papers and n = 550 digital complete surveys. From 734 total respondents, 62.0% declared VD supplementation. The main personal rationale for VD supplementation were recommendation of medical specialist 172 (37.8%) and self-education 135 (29.7%). The main reasons for non-supplementation of VD were lack of knowledge about VD 159 (57.0%) and lack of motivation 77 (27.6%). VD supplementation was independently associated with a family doctor (odds ratio (OR), 95% confidence interval (CI): 4.67, 2.32–9.40) or medical specialist recommendation (16.20, 9.57–27.43), and self-education (5.97, 3.90–9.13). Most Polish individuals with T1DM use VD supplements, and the decision is related to physicians’ recommendations and self-education.

The Role of Vitamin D in Fertility and during Pregnancy and Lactation: A Review of Clinical Data

Vitamin D deficiency is common and there exists a huge gap between recommended dietary vitamin D intakes and the poor vitamin D supply in the general population. While vitamin D is important for musculoskeletal health, there are accumulating data suggesting that vitamin D may also be important for fertility, pregnancy outcomes and lactation. Significant changes in vitamin D metabolism during pregnancy such as increased production of the “active vitamin D hormone” calcitriol support the important role of vitamin D in this setting. Observational studies show that vitamin D deficiency is a risk marker for reduced fertility and various adverse pregnancy outcomes and is associated with a low vitamin D content of breast milk. Meta-analyses of randomized controlled trials (RCTs) document that physiological vitamin D supplementation during pregnancy is safe and improves vitamin D and calcium status, thereby protecting skeletal health. Although certain RCTs and/or meta-analyses reported some other beneficial effects, it is still not clear whether vitamin D supplementation improves fertility or decreases the risk of adverse pregnancy outcomes such as low birth weight, pre-eclampsia and neonatal mortality, or reduces wheeze/asthma in the infants. Nevertheless, vitamin D supplementation in pregnant women is frequently required to achieve a sufficient vitamin D status as recommended by nutritional vitamin D guidelines. In this review, we provide an overview of systematic reviews, meta-analyses and large trials reporting clinical data on the role of vitamin D for fertility, pregnancy and lactation.