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Vitamin D supplements deliver safer births but reduce fertility

2016-05-18     Permalink::
 Vitamin D insufficiency is common in fertile women
 Previous studies have shown association between vitamin D insufficiency and low birth weight, reduced fertility and adverse pregnancy outcomes.
 Daily vitamin D supplements caused fewer childbirth complications, but did not improve birth weight
 Surprisingly, high dose of vitamin D supplementation was shown to reduce chances of conceiving.

Gitte Bloch Rasmussen
Gitte Bloch Rasmussen
May 18, 2016, Rome, Italy. Press Dispensary. New research has established that high doses of vitamin D supplements can lead to fewer complications during childbirth but reduce a woman's chances of getting pregnant in the first place.

The news was announced in Rome today by the Danish medical doctor and PhD Gitte Bloch Rasmussen, speaking at ECTS 2016, the 43rd annual congress of the European Calcified Tissue Society (ECTS).

Dr Rasmussen was reporting on trials that had been conducted among 193 women with low levels of vitamin D, who were all planning pregnancy and all attended a single centre in Aarhus, Denmark. The trials had been conducted by Dr Rasmussen with colleagues from Aarhus University Hospital, in Denmark.

Dr Rasmussen said: "Fertile women are often found to have low vitamin D levels, which are associated with low birth weight, reduced fertility and adverse pregnancy outcomes. Our aim was to look at the effects of vitamin D supplements on these areas in women with low levels of vitamin D."

The 193 women were aged 20 - 40, were planning pregnancy and had levels of 25-hydroxyvitamin D (known as 25OHD, the most accurate way to measure vitamin D levels) below 50 nmol/L, which is bordering on insufficiency. Before conceiving, they were allocated to groups, one being given a 70mcg daily supplement of vitamin D3 and one a 35mcg daily dose, with matching groups given placebos. The women continued the trial until 16 weeks after birth and were evaluated for their 25OHD level, birth weight, fertility and any complications.

56% of the women conceived within 12 months, 38% in the placebo group, 29% taking the 70mcg supplement and 33% taking the 35mcg supplement. 44% did not conceive.

Dr Rasmussen continued: "We found a noticeable difference in two of the four areas we evaluated. Whilst the lower daily dose of vitamin D3 did not significantly affect the chances of pregnancy, the higher 70mcg daily supplement significantly reduced the chances of conceiving.  On the other hand, supplementation showed to be beneficial on risk of complications during labour, as these were significantly less frequent in the combined vitamin D3 groups (a 23% risk) than in the placebo group (a 52% risk).

"However, birth weight did not differ significantly between those treated with vitamin D3 and those receiving placebos; there were also no differences between groups on any safety measures."

Dr Rasmussen concluded: "High doses of vitamin D3 may reduce the likelihood of conceiving, but may also be associated with fewer complications during childbirth, though without improving birth weight."

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Gitte Bloch Rasmussen ECTS 2016
Full size images available for download at

Notes for editors

About the trial

This was an investigator-initiated double-blind, randomized, placebo-controlled, parallel-group trial from a single centre, involving a total of 193 women planning pregnancy (20-40 years old) with 25OHD level below 50 nmol/L.

Daily supplementation of cholecalciferol 70 mcg (2800 IU) (70-VitD3), 35 mcg (1400 IU) (35-VitD3) or matching placebo was administered before conceiving and continued until 16 weeks post partum. 25OHD, birth weight, fertility, and complication were evaluated.

Baseline level of 25OHD did not differ between groups (mean 43 nmol/L; p=0.91). Levels of 25OHD increased dose-dependently in response to treatment (p < 0.001).

A total of 108 women (56%) conceived within 12 months after randomization, 41 (38%) in the placebo group, 31 (29%) in the 70-VitD3, and 36 (33%) in the 35-VitD3 group. Compared with placebo, the 35-VitD3 group did not affect pregnancy chances significantly (HR: 0.79; 95% CI: 0.48, 1.28), but chances of conceiving were significantly reduced by a daily supplement of 70 mcg (HR: 0.52; 95% CI: 0.31, 0.87). Birth weight did not differ significantly between the vitamin D3 treated and the placebo group. Complications during labour were significantly more frequent in the placebo- compared with the combined vitamin D3 group (52% vs. 23%, p < 0.005), although specific complications did not differ between groups. There were no differences between groups on any safety measures.

The trial concluded that high doses of vitamin D3 (70 mcg/daily) may reduce the likelihood of conceiving but may also be associated with fewer complications during childbirth without affecting birth weight.

Approved by The Ethical Committee of Denmark (M-20090097).

About ECTS 2016

ECTS 2016 is the 43rd annual congress of the European Calcified Tissue Society (ECTS), held in Rome, Italy on May 14-17, 2016, in collaboration with the Cancer and Bone Society.

ECTS 2016 gives delegates the opportunity to collaborate with leading international researchers and clinical colleagues. Main discussion points are the latest in high quality science and research to benefit clinical practice.

ECTS 2017, the 44th congress, will be held in Salzberg, Austria, May 13-16, 2017.
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About The European Calcified Tissue Society

The European Calcified Tissue Society (ECTS) is the major organisation in Europe for researchers and clinicians working in the field of calcified tissues and related fields. ECTS acts as a forum for the dissemination of high quality research through its annual meeting, the European Symposium on Calcified Tissues, and through training courses and workshops.

Calcified tissues are central to a healthy skeleton and to bone disorders - such as osteoporosis, back pain and fractures - that make life a misery for countless people. Children can inherit some forms of bone diseases causing bone pain, shortness and deformed limbs.

For further information, please contact:
Roberta Mugnai, ECTS executive director
European Calcified Tissue Society (ECTS)
Tel: + 32 476 520 716

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Published for European Calcified Tissue Society (ECTS) by Press Dispensary