Is It Possible to Get Pregnant and Get Pregnant Again
Can a woman get pregnant when she is already pregnant? In other words, tin she have ii foetuses in her uterus at unlike stages of evolution?
The technical term for this is superfetation. In humans, information technology'due south possible, but it'southward very uncommon.
Two 1000 years ago, that great Greek thinker Aristotle wondered about this very topic, specifically as regards the hare.
Aristotle noticed that when a hare gave birth, quite often the offspring in a single litter would fall into two distinct classes: there would exist a bunch of total-sized robust babe hares, and another bunch of scrawny frail baby hares.
It was, he idea, as though the mother hare had become pregnant and so — while significant — had conceived a 2d time.
At that place was nothing fundamentally wrong with the smaller, weedy offspring, Aristotle thought, apart from the fact that they had not spent enough time growing in their mother's uterus. And he was right.
Why is it so rare?
Normally in humans, at that place are iii split up barriers to stop a female from getting pregnant once again if she is already pregnant.
The first barrier is the hormonal changes after conception that stop the ovaries from releasing some other egg.
The second barrier is concrete: a mucous plug. Near immediately afterwards conception, a plug forms in the neck and sits at the elevation of the vagina. This plug stops any other sperm from entering the uterus and getting to a second egg.
Third, at that place are physical and chemical changes that happen to the inner lining of the uterus in pregnancy. These changes normally finish a second fertilised egg from being able to adhere to the uterine wall.
Nevertheless, some beast species manage to go around all these barriers. About ane to ii per cent of all pregnant cows show signs of being potentially fertile while they are already significant, and superfetation has been observed in animals such equally 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 instance is that of Julia Grovenburg, a 31-twelvemonth-old woman from Arkansas.
Ms Grovenburg and her partner had been trying to go pregnant for 3 years, and had begun to consider adoption of a child.
But amazingly she conceived twice in 2009 — a few weeks apart. The Daily Mail service claimed that, in a "desperate and last attempt to have children of their own", the couple had given it one final try.
This is a curious use of the word desperate.
I might be old-fashioned, simply it seems odd to me to regard sexual intercourse as "a desperate and terminal attempt" to get pregnant.
Information technology makes you wonder what measures they tried before they got desperate.
Anyhow, Ms Grovenburg was pregnant — but then things went odd: the ultrasound showed two independent babies, each living in their own divide amniotic sac. But 1 was much larger and more developed than the other.
Every bit the ultrasounds scans mounted upwards for Ms Grovenburg, both foetuses seemed to exist growing normally and healthily, though information technology appeared as if 1 foetus had simply started a few weeks subsequently the other.
In other words, Mrs Grovenburg had conceived a second baby a few weeks after becoming significant with the starting time.
No mode to prove it
Now nosotros don't take rock-solid proof that this is what happened. Nosotros would need a serial of ultrasound scans to prove that.
These scans would need to document a serial of changes — starting with no foetus or amniotic sac in the uterus, and so a single foetus in its single amniotic sac, and a second foetus appearing in their own second amniotic sac later on a few weeks.
People don't ordinarily get a series of ultrasound scans immediately after sexual intercourse, so this kind of difficult data is difficult to get.
Only in that location is some evolutionary biological science backside superfetation. Female person European brown hares often have a second pregnancy while already significant. This means females tin can have about one third more offspring in each breeding flavour.
For humans, more babies each breeding cycle isn't always a plus — specially if you lot're trying to get 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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