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Pregnancy Timeline by SemestersDevelopmental TimelineFertilizationFirst TrimesterSecond TrimesterThird TrimesterFirst Thin Layer of Skin AppearsEnd of Embryonic PeriodEnd of Embryonic PeriodFemale Reproductive SystemBeginning Cerebral HemispheresA Four Chambered HeartFirst Detectable Brain WavesThe Appearance of SomitesBasic Brain Structure in PlaceHeartbeat can be detectedHeartbeat can be detectedFinger and toe prints appearFinger and toe prints appearFetal sexual organs visibleBrown fat surrounds lymphatic systemBone marrow starts making blood cellsBone marrow starts making blood cellsInner Ear Bones HardenSensory brain waves begin to activateSensory brain waves begin to activateFetal liver is producing blood cellsBrain convolutions beginBrain convolutions beginImmune system beginningWhite fat begins to be madeHead may position into pelvisWhite fat begins to be madePeriod of rapid brain growthFull TermHead may position into pelvisImmune system beginningLungs begin to produce surfactant
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Customizing vitamin D may benefit pregnant women

Individualized vitamin D supplements help protect pregnant women from its deficiency. Tailored doses may compensate for individual risk factors and even protect bones.


Vitamin D is a hormone that helps the body absorb calcium. It plays a crucial role in bone and muscle health. Skin naturally produces vitamin D after being exposed to sunlight. But, people can also obtain smaller amounts of it via food — such as milk fortified with vitamin D.

Vitamin D deficiency is common, even among pregnant women. Evidence suggests such a deficiency in pregnancy can harm not only mom's health, but fetal development — and a child's long-term skeletal health.

According to a new study published in the Endocrine Society's Journal of Clinical Endocrinology & Metabolism, researchers found vitamin D supplements are less effective at raising vitamin D levels in pregnant women who deliver in the winter, have low levels of vitamin D early in pregnancy, or who gain more than normally expected weight during pregnancy. Women with such risk factors may need increased vitamin D dosage during their pregnancy — more than other mothers-to-be.


"It is critical for pregnant women to have sufficient levels of vitamin D for the health of their babies.

"Our study findings suggest that in order to optimize vitamin D concentrations through pregnancy, the supplemental dose given may need to be tailored to a woman's individual circumstances, such as her anticipated season of delivery."


Nicholas C. Harvey, MA, MB, BChir, MRCP, PhD, Professor of Rheumatology and Clinical Epidemiology at the University of Southampton in Southampton, United Kingdom.


The analysis examined data from the Maternal Vitamin D Osteoporosis Study (MAVIDOS), a multi-center, double-blind, randomized, placebo-controlled trial of vitamin D supplements given in pregnancy. The study examined vitamin D levels in 829 pregnant women who received early pregnancy ultrasounds at one of three United Kingdom hospitals.

Beginning around 14 weeks' gestation, women were randomized to receive either a 1000 IU/day dose of a vitamin D3 supplement called cholecalciferol — or of a placebo. Researchers measured vitamin D levels in participants' blood prior to the start of the study and again at 34 weeks' gestation.

Participants who received the D supplement had varying levels of vitamin D in their blood, even though they each received the same dose.


Researchers found women who delivered in the summer, gained less weight during pregnancy, and had higher vitamin D levels early in pregnancy — tended to have higher blood levels of vitamin D than their counterparts.


"Varied responses to vitamin D supplementation according to individual attributes can be used to tailor approaches to prenatal care," says Cyrus Cooper OBE, MA, DM, FRCP, FFPH, FMedSci, Professor of Rheumatology and Clinical Epidemiology at the University of Southampton's MRC Lifecourse Epidemiology Unit, and one of the study's authors. "This work will inform the development of strategies to enhance bone development across generations."

Abstract Context:
Current approaches to antenatal vitamin D supplementation do not account for interindividual differences in 25-hydroxyvitamin D (25(OH)D) response.

Objective:
We assessed which maternal and environmental characteristics were associated with 25(OH)D after supplementation with cholecalciferol.
Design:
Within-randomization-group analysis of participants in the Maternal Vitamin D Osteoporosis Study trial of vitamin D supplementation in pregnancy.

Setting:
Hospital antenatal clinics.

Participants:
A total of 829 pregnant women (422 placebo, 407 cholecalciferol). At 14 and 34 weeks of gestation, maternal anthropometry, health, and lifestyle were assessed and 25(OH)D measured. Compliance was determined using pill counts at 19 and 34 weeks.
Interventions:
1000 IU/d of cholecalciferol or matched placebo from 14 weeks of gestation until delivery.

Main Outcome Measure:
25(OH)D at 34 weeks, measured in a single batch (Diasorin Liaison).

Results:
25(OH)D at 34 weeks of gestation was higher in the women randomized to vitamin D (mean [SD], 67.7 [21.3] nmol/L) compared with placebo (43.1 [22.5] nmol/L; P < .001). In women randomized to cholecalciferol, higher pregnancy weight gain from 14 to 34 weeks of gestation (kg) (β = −0.81 [95% confidence interval −1.39, −0.22]), lower compliance with study medication (%) (β = −0.28 [−0.072, −0.48]), lower early pregnancy 25(OH)D (nmol/L) (β = 0.28 [0.16, 0.40]), and delivery in the winter vs the summer (β = −10.5 [−6.4, −14.6]) were independently associated with lower 25(OH)D at 34 weeks of gestation.

Conclusions:
Women who gained more weight during pregnancy had lower 25(OH)D in early pregnancy and delivered in winter achieved a lower 25(OH)D in late pregnancy when supplemented with 1000 IU/d cholecalciferol. Future studies should aim to determine appropriate doses to enable consistent repletion of 25(OH)D during pregnancy.

The study, "Determinants of the Maternal 25-hydroxyvitamin D Response to Vitamin D Supplementation During Pregnancy," will be published online at http://press.endocrine.org/doi/10.1210/jc.2016-2869, ahead of print.

Other authors of the study include: Rebecca J. Moon, Stefania D'Angelo, Sarah R. Crozier, Hazel M. Inskip, Elaine M. Dennison and Sian M. Robinson of Southampton General Hospital in Southampton, U.K.; Inez Schoenmakers and Ann Prentice of the Elsie Widdowson Laboratory in Cambridge, U.K.; Nigel K. Arden, Andrew Carr and M. Kassim Javaid of the University of Oxford in Oxford, U.K.; Nicholas J. Bishop of Sheffield Children's Hospital and the University of Sheffield in Sheffield, U.K.; Richard Eastell of the University of Sheffield in Sheffield, U.K.; Robert Fraser and Saurabh V. Gandhi of the Sheffield Hospitals NHS Trust in Sheffield, U.K.; Keith M. Godfrey of Southampton General Hospital and the University of Southampton in Southampton, U.K.; Stephen Kennedy and Aris T. Papageorghiou of John Radcliffe Hospital at the University of Oxford in Oxford, U.K.; M. Zulf Mughal of Royal Manchester Children's Hospitals in Manchester, U.K.; and David M. Reid at the University of Aberdeen in Aberdeen, U.K.

The research was supported by grants from Arthritis Research UK, Medical Research Council, Bupa Foundation, National Institute for Health Research (NIHR) Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, and NIHR Musculoskeletal Biomedical Research Unit, University of Oxford. Merck GmbH provided the vitamin D supplement used in the study.

Endocrinologists are at the core of solving the most pressing health problems of our time, from diabetes and obesity to infertility, bone health, and hormone-related cancers. The Endocrine Society is the world's oldest and largest organization of scientists devoted to hormone research and physicians who care for people with hormone-related conditions.

The Society, which is celebrating its centennial in 2016, has more than 18,000 members, including scientists, physicians, educators, nurses and students in 122 countries. To learn more about the Society and the field of endocrinology, visit our site at http://www.endocrine.org. Follow us on Twitter at @TheEndoSociety and @EndoMedia.

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Nov 1, 2016   Fetal Timeline   Maternal Timeline   News   News Archive   



Women who deliver in the summer, gain less weight in pregnancy, have higher vitamin D in
their blood early in pregnancy — keep higher levels of vitamin D over their counterparts.
Image Credit: Public Domain


 


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