Understanding changes in the cervix before birth

Scientists may have found a new way to prevent premature labour and to induce labour if a baby is struggling by using hormones called androgens.

Before going into labour, a woman’s cervix changes: it gets softer and more stretchy so that the baby is able to leave the womb. This is known as cervical ripening. Understanding how this works is important. If the cervix ripens too early, this can lead to premature birth. If it doesn’t ripen properly, then it will make giving birth difficult.

Certain types of hormones in the body, called androgenic hormones, stop the cervix from ripening. By changing the levels of these hormones, we could use them both to stop premature labour, and to induce labour if a baby is struggling in the womb.

We think that androgenic hormones might work by keeping other natural substances in the womb in check until a woman is ready to go into labour. Scientists found that exposing the cervixes of mice to androgens blocks these substances from acting. This is turn means that the cervix stays firm, and keeps the baby in the womb.

In humans, we also found that androgens become less active when a woman is ready to go into labour. This suggests that androgens work during pregnancy to keep the cervix firm. When they stop acting, the cervix softens, and labour begins.

We presented our early findings at a meeting of the Society of Reproductive Investigation in March 2016. We believe that our work will lay the foundation for trials of using androgen blockers, which stop androgen hormones from working, as ways to make the cervix ripen. This would be a huge step forward in ways we can induce labour. Inducing labour when a baby is struggling in the womb can make a big difference to its chances of a healthy life. 

Waters breaking early

In work related to this, we also looked at the genes that were active in women whose waters broke too early. This is known as premature pre-labour rupture of fetal membranes (PPROM). Normally, a woman’s waters break around the time that the baby is due, but sometimes it can happen earlier. Waters breaking early can, but doesn’t always, lead to premature birth.

Scientists looked at samples from the cervixes of women who had delivered too early. Compared to women who delivered on time, they found that some genes were only active in women who experienced PPROM, and gave birth to their baby prematurely. We think that these genes may also play a role in the ripening of the cervix before birth. 

Researchers

Jane Norman, Philippa Saunders, Gunvor Ekman-Ordeberg, Sofia Makieva

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Funding

This study is fully funded by Tommy's and takes place in a Tommy's centre

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