A Woman Can Fall Pregnant Agains While Pregnant
Can a woman get meaning when she is already significant? In other words, can she have ii foetuses in her uterus at different stages of development?
The technical term for this is superfetation. In humans, it's possible, merely information technology'south very uncommon.
Two thousand years ago, that great Greek thinker Aristotle wondered nigh this very topic, specifically as regards the hare.
Aristotle noticed that when a hare gave nativity, quite oft the offspring in a single litter would fall into two distinct classes: in that location would be a bunch of full-sized robust baby hares, and another bunch of scrawny frail baby hares.
It was, he idea, as though the mother hare had become pregnant and then — while pregnant — had conceived a 2nd time.
There was nothing fundamentally wrong with the smaller, weedy offspring, Aristotle thought, apart from the fact that they had not spent plenty time growing in their mother's uterus. And he was right.
Why is it so rare?
Commonly in humans, there are 3 dissever barriers to stop a female from getting significant again if she is already meaning.
The first barrier is the hormonal changes later formulation that finish the ovaries from releasing some other egg.
The 2d bulwark is physical: a mucous plug. Nigh immediately after formulation, a plug forms in the cervix and sits at the top of the vagina. This plug stops any other sperm from entering the uterus and getting to a 2nd egg.
Third, there are physical and chemical changes that happen to the inner lining of the uterus in pregnancy. These changes commonly stop a second fertilised egg from being able to adhere to the uterine wall.
Withal, some creature species manage to get effectually all these barriers. About 1 to 2 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-yr-old woman from Arkansas.
Ms Grovenburg and her partner had been trying to go significant for three years, and had begun to consider adoption of a child.
But amazingly she conceived twice in 2009 — a few weeks apart. The Daily Mail claimed that, in a "drastic and final attempt to take children of their own", the couple had given it one last endeavour.
This is a curious use of the discussion desperate.
I might exist old-fashioned, but it seems odd to me to regard sexual intercourse as "a drastic and final attempt" to become pregnant.
Information technology makes you lot wonder what measures they tried earlier they got desperate.
Anyhow, Ms Grovenburg was pregnant — but and then things went odd: the ultrasound showed two contained babies, each living in their own split amniotic sac. Just one was much larger and more developed than the other.
Equally the ultrasounds scans mounted upwardly for Ms Grovenburg, both foetuses seemed to be growing normally and healthily, though it appeared as if ane foetus had just 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 first.
No way to show information technology
At present we don't have rock-solid proof that this is what happened. Nosotros would need a serial of ultrasound scans to prove that.
These scans would demand to document a serial 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 second amniotic sac afterward a few weeks.
People don't usually get a series of ultrasound scans immediately after sexual intercourse, then this kind of hard data is difficult to get.
But there is some evolutionary biology behind superfetation. Female European brown hares oft accept a second pregnancy while already pregnant. This means females tin have nigh one third more offspring in each convenance flavour.
For humans, more babies each breeding cycle isn't e'er a plus — especially if you're trying to get a proficient night'southward sleep.
Posted , updated
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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