Is It Possible for a Pregnant Woman to Get Pregnant Again
Can a woman get pregnant when she is already pregnant? In other words, tin she take two foetuses in her uterus at different stages of evolution?
The technical term for this is superfetation. In humans, it'due south possible, but it's very uncommon.
Two thousand years ago, that groovy Greek thinker Aristotle wondered about this very topic, specifically as regards the hare.
Aristotle noticed that when a hare gave nascence, quite oftentimes the offspring in a single litter would autumn into two singled-out classes: in that location would be a bunch of full-sized robust infant hares, and some other bunch of scrawny fragile baby hares.
It was, he thought, as though the mother hare had become pregnant then — while pregnant — had conceived a second time.
There was nothing fundamentally wrong with the smaller, weedy offspring, Aristotle idea, apart from the fact that they had non spent plenty time growing in their mother's uterus. And he was right.
Why is it and then rare?
Normally in humans, at that place are three dissever barriers to stop a female person from getting pregnant again if she is already pregnant.
The kickoff bulwark is the hormonal changes after conception that stop the ovaries from releasing another egg.
The 2d bulwark is concrete: a mucous plug. Almost immediately after conception, a plug forms in the cervix and sits at the tiptop of the vagina. This plug stops any other sperm from entering the uterus and getting to a second egg.
Third, there are physical and chemical changes that happen to the inner lining of the uterus in pregnancy. These changes usually stop a second fertilised egg from being able to attach to the uterine wall.
Nevertheless, some animal species manage to get around all these barriers. Near ane to ii per cent of all pregnant cows show signs of being potentially fertile while they are already pregnant, and superfetation has been observed in animals such as the mouse, the rabbit, the sheep, the buffalo, the mink, and the Australian swamp wallaby.
Could superfetation happen to me?
Superfetation is extremely uncommon in humans, with fewer than a dozen cases in the medical literature.
A typical case is that of Julia Grovenburg, a 31-twelvemonth-old adult female from Arkansas.
Ms Grovenburg and her partner had been trying to get meaning for three years, and had begun to consider adoption of a child.
Simply amazingly she conceived twice in 2009 — a few weeks apart. The Daily Post claimed that, in a "desperate and final try to have children of their ain", the couple had given it one last endeavour.
This is a curious use of the word drastic.
I might be onetime-fashioned, but it seems odd to me to regard sexual intercourse as "a desperate and final attempt" to get pregnant.
It makes yous wonder what measures they tried before they got desperate.
Anyhow, Ms Grovenburg was pregnant — but and then things went odd: the ultrasound showed two contained babies, each living in their ain separate amniotic sac. Simply one was much larger and more developed than the other.
As the ultrasounds scans mounted upward for Ms Grovenburg, both foetuses seemed to be growing normally and healthily, though it appeared as if one foetus had but started a few weeks afterward the other.
In other words, Mrs Grovenburg had conceived a second infant a few weeks after becoming pregnant with the first.
No way to prove it
Now we don't accept rock-solid proof that this is what happened. We would demand a series of ultrasound scans to prove that.
These scans would demand to document a series of changes — starting with no foetus or amniotic sac in the uterus, and then a single foetus in its unmarried amniotic sac, and a second foetus appearing in their ain 2nd amniotic sac later a few weeks.
People don't commonly get a series of ultrasound scans immediately after sexual intercourse, so this kind of hard information is difficult to get.
But there is some evolutionary biology behind superfetation. Female European brown hares ofttimes accept a 2nd pregnancy while already significant. This means females tin can take about one 3rd more offspring in each breeding season.
For humans, more than babies each convenance cycle isn't always a plus — especially if you're trying to become a good night's sleep.
Posted , updated
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Source: https://www.abc.net.au/news/science/2017-04-11/dr-karl-superfetation-can-you-get-pregnant-during-pregnancy/8430238
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