Science Bites seeks to compile the latest scientific research updates in bite-sized forms.

1. Preventing miscarriage by carefully timing a pregnancy

A carefully timed pregnancy may prevent miscarriage, suggest researchers. According to Professor Jan Brosens from the University of Warwick, stem cells in a healthy uterus allow endometrial lining to build up after each menstrual cycle. When these cells senesce, they stop dividing and trigger inflammation. Natural killer (NK) cells then clear out the ageing cells in the endometrial lining, creating “holes” that allow the embryo to implant.

Based on samples taken from women’s uteruses, researchers discovered that the numbers of NK cells cycled in a predictable manner throughout the month in women who have not had miscarriages, but varied in women who have miscarried few times – increasing continuously for several months, before depleting and then accumulating again.

“40% of (recurrent miscarriage) patients had no stem cells at all,” Brosens revealed, adding that large accumulated numbers of NK cells lead to bigger holes in the endometrium that initially makes it easy for an embryo to embed, which explains why women who frequently miscarry find it easy to conceive. However, the structure eventually collapses in on itself, and leads to a miscarriage he added.

Theorising that women who often miscarry may be conceiving at times when the uterus is not in its optimal condition, Brosens and his colleagues have begun to offer tests to check levels of NK cells and identify the best time to conceive. The findings are anecdotal and further clinical trials are necessary, but if the approach is successful, it can also be useful in in-vitro fertilisation treatments.

2. Antibiotics associated with increased risk of miscarriage

A recent review involving over 95,000 women between 1998 and 2009 has revealed that five classes of common antibiotics, namely macrolides, quinolones, tetracyclines, sulfonamids and metronidazole, could lead to an increased risk of miscarriage in early stages of pregnancy.

On the other hand, erythromycin and nitrofurantoin, which are often used to treat urinary tract infections in expectant mothers, were not associated with an increased risk.

“Infections are prevalent during pregnancy,” said Dr Anick Berard from the Facutly of Pharmacy at the Universite de Montreal. “Although antibiotic use to treat infections has been linked to a decreased risk of prematurity and low birth weight in other studies, our investigation shows that certain types of antibiotics are increasing the risk of spontaneous abortion, with 60 per cent to two-fold increase.”

Researchers noted that a confounder to the increased risk of miscarriage may also be from the infection itself, but have adjusted the variable during their analysis.

“Given that the baseline risk of spontaneous abortion can go as high as 30%, this is significant. Nevertheless, the increased risk was not seen for all antibiotics, which is reassuring for users,” Berard said.

According to general practitioner Nicola Davies, most of these drugs would not be prescribed to patients who are pregnant. “The main risk this research throws up is for those women who don’t know they are pregnant,” Davies said.

3. Smoking in pregnancy tied to autism in future generation

Women who smoke during their pregnancy may increase the risk of autistic traits in their future granddaughters, suggest findings of a recent study.

Based on three generations of data from 14,5000 participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), researchers from the University of Bristol discovered that a girl is 67% more likely to display traits related to autism, such as poor social communication skills and repetitive behaviours, if their maternal grandmothers smoked during pregnancy. The team also found that it also raised the of being diangosed autism spectrum disorder (ASD) by 53%.

“The associations we observe raise intriguing issues on possible transgenerational influences in autism. Future research will help understand the meaning and mechanisms behind these findings,” said study author Dr Dheeraj Rai.

As the smoking effect was only observed in girls, researchers posit that smoking damages the mitochondrial DNA, which are passed down the female line.

“We already know that protecting a baby from tobacco smoke is one of the best things a woman can do to give her child a healthy start in life,” said study co-author Professor Jean Golding. “Now we’ve found that not smoking during pregnancy could also give their future grandchildren a better start too.”

“We have started studying the next generation of participants, so eventually we will be able to see if the effect carries down from the great-grandparents to their great-grandchildren too,” Golding added. MIMS

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