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Chinese neonates 3.6 X more likely to have low vitamin D if previous month was cold – May 2024

Associations of ambient temperature and total cloud cover during pregnancy with newborn vitamin D status

Public Health, . 2024 Jun:231:179-186. doi:10.1016/j.puhe.2024.03.026 PDF behind paywall
J Liu 1, X Fang 1, S Cao 1, Y Shi 1, S Li 1, H Liu 1, Y Li 1, S Xu 1, W Xia 2

Objectives: We aimed to estimate the effects of temperature and total cloud cover before birth on newborn vitamin D status.

Study design: Prospective birth cohort.

Methods: This study included 2055 mother-newborn pairs in Wuhan, Hubei province, China. The data of temperature and total cloud cover from 30 days before birth were collected, and cord blood 25-hydroxyvitamin D [25(OH)D] were determined. Restricted cubic spline regression models, multiple linear regression models, and logistic regression models were applied to estimate the associations.

Results: A "J" shaped curve was observed between temperature and vitamin D status, and an inverse "J" shaped curve was observed between total cloud cover and vitamin D status.
Compared to the fourth quartile (75-100th percentile, Q4) of average temperature (30 days before birth), the odds ratio (OR) for Q1 (0-25th percentile) associated with the vitamin D deficiency occurrence (<20 ng/mL) was 3.63 (95% CI, 1.54, 8.65).
Compared to Q1 of the average total cloud cover (30 days before birth), the OR associated with the occurrence of vitamin D deficiency was 2.38 (95% CI, 1.63, 3.50) for the Q4.

Conclusions: Low temperature and high cloud cover before delivery were significantly associated with an increased probability of vitamin D deficiency in newborns. The findings suggested that pregnancy women lacking sufficient sunlight exposure still need vitamin D supplement to overcome the potential vitamin D deficiency status.

Introduction
Vitamin D status during pregnancy is not only important for the mother and growing fetus, but also have long-term effects on children after birth.1,2 Vitamin D deficiency has an adverse impact on the human skeletal system, and even facilitates the development and progression of many maladies, including infectious diseases, skin disorders, hypercalcaemia, and cancer.2, 3, 4, 5 For newborns, due to the fact that cord blood vitamin D levels reflects the transfer degree of 25-hydroxyvitamin D [25(OH)D] from mother to fetus,6 evaluating factors affecting newborn vitamin D levels may provide a new perspective for maintaining optimal vitamin D levels and promoting maternal and infant health.

The primary endogenous source of vitamin D in humans is the vitamin D3 synthesized in the epidermis. Vitamin D3 is formed by isomerization of pre-vitamin D3, which is photoconverted by 7-Dehydrocholesterol through exposure to ultraviolet (UV) light.2,3 Vitamin D2 (another form of vitamin D) comes from some plants in diet and can be produced by some yeasts.7 The intake of vitamin D2 or D3 enter the venous blood after absorbed by the intestine.7 In the liver, both vitamin D2 and D3 are converted to 25(OH)D by the process of hydroxylation.2,8 The 1,25-dihydroxyvitamin D [1,25(OH)2D], which is the biologically active form, performs pleiotropic health regulatory effects.9, 10, 11 However, 1,25(OH)2D was not used as the biomarker due to the short circulating half-life and low circulating concentration.7 Serum 25(OH)D with a circulating half-life of 2–3 weeks is recommended as the main metabolite for measuring vitamin D status.7

The basic environmental determinant influencing synthesis capacity of vitamin D is the solar zenith angle, which controls the potential available ultraviolet via latitude, season and time of day.12 Previous population-based studies have confirmed the associations between sunlight exposure and vitamin D levels.13, 14, 15, 16, 17 However, atmospheric variables, such as temperature and total cloud cover, could be confounding factors influencing vitamin D status. High cloud cover levels can reduce the effective irradiances of vitamin D compared to the clear-sky cases.18,19 The temperature can affect behaviors, including clothing wearing and the time participating in outdoor activity.13,20 In addition, Ultraviolet radiation and vitamin D status can influence pregnancy outcomes and offspring health.21 However, few population studies focused on the impacts of meteorological factors on newborn vitamin D levels.

Thus, based on a prospective birth cohort study, we aimed to explore the relationships between meteorological factors (temperature and total cloud cover during pregnancy) during pregnancy and newborn vitamin D. Considering the half-life of 25(OH)D in cord blood and the short-term effects of meteorological factors, we examined the total cloud cover and temperature from 30 days before birth to explore their relationships with 25(OH)D. Besides, the possibility of vitamin D deficiency occurrence due to the change of temperature or total cloud cover was also estimated.

Section snippets
Study population
Our study was based on a prospective birth cohort that enrolled mother–newborn pairs at the Wuhan Women and Children Medical and Health Care Center in Hubei province, China, from 2013 to 2014.22,23 During the study period, 2057 mother–newborn pairs were included: 1) residing in Wuhan with no plan to move to other cities; 2) singleton gestation (<16 weeks) without congenital disabilities; 3) performing prenatal care and delivery in the study hospital; 4) agreement to participate in follow-up; 5) …

Characteristics of included mother–newborn pairs
Table 1 presents the basic characteristics of participants in the present study. The average age of mothers at delivery was 28.35 ± 3.30 years old, and the average PBMI was 20.71 ± 2.77 kg/m2. Most (79.12%) of them received more than 12 years of education. The proportion of cesarean deliveries to spontaneous labors was close (53.87%–46.13%). About 45.79% of pregnant women received multi-vitamin supplements in the early pregnancy, and 83.26% received supplements in the mid-to late pregnancy. Of…

Discussion
Vitamin D plays a crucial role in physiological functions,32, 33, 34, 35 and solar UV radiation exposure is still the primary source of vitamin D. Our results show a “J” shaped curve for the relationship between temperature and newborn vitamin D status, and an inverse “J” shaped curve for total cloud cover. The joint effect analyses indicated that the relationships between temperature and vitamin D status were relatively stable, while the relationship between total cloud cover and vitamin D…

Based on the search results, the recommended amount of vitamin D supplementation for pregnant Chinese women is 600 IU/day, according to the guidelines from the Institute of Medicine (IOM) in 2010.However, several studies have found that this recommended dose of 600 IU/day results in suboptimal vitamin D levels in pregnant Chinese women and their newborns. The studies report a high prevalence of vitamin D deficiency or insufficiency among pregnant women in China, ranging from 90.5% to 98.4%.
Some key findings:

  • A study in Beijing found that all (100%) pregnant women and newborns had vitamin D levels below 75 nmol/L, which is considered insufficient.
  • In Shanghai, only 1.6% of 34,417 pregnant women had adequate vitamin D levels (≥75 nmol/L) when supplemented with the IOM recommendation of 600 IU/day.
  • The latest China Nutrition and Health Surveillance in 2015-2017 found that only 12.57% of pregnant women had sufficient vitamin D levels, a significant decrease from 25.2% in 2010-2012.

Several studies suggest that higher doses of vitamin D supplementation, such as 4000 IU/day, may be required to achieve vitamin D sufficiency in most pregnant Chinese women and their neonates. However, the optimal dosage is still under debate.
Perplexity full answer includes many references

VitaminDWiki - Pregnancy category contains

897 items in Pregnancy category

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VitaminDWiki – Healthy pregnancies need lots of vitamin D contains

Problem
Vit. D
Reduces		Evidence
0. Chance of not conceiving3.4 times Observe
1. Miscarriage 2.5 times Observe
2. Pre-eclampsia 3.6 timesRCT
3. Gestational Diabetes 3 times RCT
4. Good 2nd trimester sleep quality 3.5 times Observe
5. Premature birth 2 times RCT
6. C-section - unplanned 1.6 timesObserve
     Stillbirth - OMEGA-3 4 timesRCT - Omega-3
7. Depression AFTER pregnancy 1.4 times RCT
8. Small for Gestational Age 1.6 times meta-analysis
9. Infant height, weight, head size
     within normal limits		 RCT
10. Childhood Wheezing 1.3 times RCT
11. Additional child is Autistic 4 times Intervention
12.Young adult Multiple Sclerosis 1.9 timesObserve
13. Preeclampsia in young adult 3.5 timesRCT
14. Good motor skills @ age 31.4 times Observe
15. Childhood Mite allergy 5 times RCT
16. Childhood Respiratory Tract visits 2.5 times RCT

RCT = Randomized Controlled Trial

VitaminDWiki - 9 studies of Pregnancy in the Orient

This list is automatically updated

VitaminDWiki - Caesarean birth much more likely if low Vitamin D - many studies

Table of Contents as of May 2024

  • C-section 3.8 X more likely when vitamin D less than 15 ng - 2009
    • VITAMIN D DEFICIENCY ASSOCIATED WITH GREATER RATES OF CESAREAN SECTIONS (news release 2009)
  • MSNBC noted that 1/3 of the births in Asia, Latin American, and the US are now caesarean and it is now 1/2 = 50% of the births in China

(13+ VitaminDWiki Pregnancy pages have CAESAREAN etc in the title

  • See also web
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Chinese neonates 3.6 X more likely to have low vitamin D if previous month was cold – May 2024        
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