Oestrogen helps to keep open the artery carrying oxygen-rich blood to the foetus.

雌激素可使动脉血管扩张，含氧量高的血液得以流向胎儿。

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Perhaps we are really talking about amniotic fluid, which surrounds the foetus in the birth sac.

也许我们真正在谈论的是羊水，也就是包围着胎儿的那些液体。

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These sound waves bounce back off the foetus, helping to create a 'picture' of the child on a screen.

这些声波在遇到胎儿时会被弹回，胎儿的“照片”也就能显示在屏幕上了。

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When the foetus has abnormalities there is no limit on the time of abortion.

BBC: NEWS | Health | Doctors grapple with abortion debate

Pity2 says this the foetus collection was also made without the parents' knowledge or consent.

BBC: You are in: Health

In pregnancy, it lengthens and becomes a barrier to help retain the foetus.

BBC: Clue to premature birth mystery