Placenta 'has key role' in determining pregnancy length
Published: 17th Nov 2010 01:27:02
The placenta may play a key role in determining the gestation period of humans and other mammals, according to a new study.
The research links growth rates of mammals inside the womb to the structure of the placenta and the way it connects mother and baby.
This, as well as mammal size, may explain variations in gestation times.
While a human pregnancy is nine months long, a meadow mouse gives birth after just three weeks.
The placenta plays a fundamental role in reproduction in mammals, transferring nutrients and oxygen from mother to foetus and removing waste from the foetus.
The structure of the placenta, however, varies enormously from species to species. This new study suggests these variations may play a role in the length of the pregnancy.
The researchers analysed 109 mammal species. What they found was the more complex and folded the placenta of a mammal, the shorter the gestation time appeared to be.
What they believe is happening is that more folded placentas are able to deliver more nutrients to the infant, spurring growth, and so reducing gestation times.
More complex placenta were found in mice, which have a gestation period of some three weeks, dogs (two months) and leopards (three months).
But humans and other primates such as baboons were seen to have simpler placentas where fewer nutrients were passing into the foetus, resulting in slower growth rates and longer gestation times.
"In humans, the placenta has simple finger-like branches with a relatively limited connection between the mother's tissues and those of the foetus," said Dr Isabella Capellini of Durham University, the lead author on the study.
"Whereas in leopards, the placenta forms a complex web of interconnections that create a larger surface area for the exchange of nutrients."
The study is published in the journal American Naturalist.
There are of course many other factors involved in gestation times, not least the size of the mammal, with larger mammals tending to have longer pregnancies.
Natural selection is also thought to determine at what stage of maturity an animal is born.
An antelope or a sea turtle must be born ready to escape predators, while mice or squirrels are born with their eyes closed and without fur, and must be guarded further by their mothers.
But the role of the placenta may go some way to explaining why gestation times can vary between mammals of similar weight.
A European porcupine, which has a highly folded placenta, has a gestation of two months. A baboon, which will grow to a similar weight, has a simpler placenta, and a gestation length of six months.
Scientists have long seen the organ as a battleground where mother and child compete for nutrients.
The new research suggests that while the offspring of mice may be winning that war, in humans, there may be a more evenly balanced contest between mother and child.
"Parent-offspring conflict is universal," said Professor Robert Barton, of Durham University, who co-authored the report.
"From the moment of conception, the physiologies of mother and baby are adapted to achieve slightly different goals in terms of how fast the baby grows."
According to Professor E Wildman of Wayne State University in Detroit, US, who reviewed the study, the research provides strong evidence of the role placenta structure plays in gestation times.
He said the work showed that "the oven was being turned up a bit" in some mammals, with more nutrients leading to faster growth rates.
At 17:05:48 in SportLeicester City manager Nigel Pearson insists he is not worried about his unresolved contract situation.
At 16:55:25 in SportHead coach Garry Monk says he will not consider his own future until Swansea City secure Premier League survival.
At 16:52:24 in EnglandA father whose son's life "ended abruptly" at Hillsborough had his dreams cut short through the "failures of others", an inquest was told.
At 16:52:17 in SportFormer Liverpool midfielder Jay Spearing believes the entire city would be lifted if the Reds end their 24-year wait to win the league title.
At 16:51:11 in BusinessThe US Food and Drug Administration (FDA) wants minimum age restrictions and health warnings on e-cigarettes.
At 16:48:47 in HeadlinesJust two months ago the message on Syria was very simple.
At 16:44:30 in Northern IrelandA nurse in the Republic of Ireland who admitted taping a patient's mouth to keep him quiet has been given the Probation Act.
At 16:44:14 in ScotlandScottish retailer Scotmid has warned it does not anticipate "a meaningful retail upturn" this year after reporting a slump in operating profits.
At 16:38:29 in ScotlandPolice have appealed for witnesses after a man was assaulted in the Cowgate area of Edinburgh on Easter Monday.
At 16:37:22 in WalesA boy accused of raping a fellow pupil at a north Wales primary school has told a jury the alleged attack never happened.
Harvard CitationBBC News, 2010. Placenta 'has key role' in determining pregnancy length [Online] (Updated 17th Nov 2010)
Available at: http://www.ukwirednews.com/news/108604/Placenta-has-key-role-in-determining-pregnancy-length [Accessed 24th Apr 2014]
News In Other Categories
The Archbishop of Canterbury has said David Cameron is "right" to state that the UK is a "Christian country".
A boy accused of raping a fellow pupil at a north Wales primary school has told a jury the alleged attack never happened.
With the doors to its brand new £1million training centre officially open, one of the UK's leading apprentice training providers, Bristol based S&B Automotive Academy, is showcasing its world-class facilities by launching a series of foreign student exchanges for the first time in its 41-year history. To get a flavour of what life is like as an apprentice in the UK, the Academy hosted 16 apprentice engineers and bus drivers from the G9 Automotive College in Hamburg, Germany, as part of a Europe-wide vocational training initiative called the ‘Leonardo Programme’ with support from the European Social Fund. In a reciprocal arrangement, S&B will be sending nine apprentices to Germany during February 2012 so that they can get an appreciation of life in the automotive industry on the Continent. A further three German exchange groups are being planned for next year. Designed to assist the development of vocational skills and training across Europe, including work placements for trainees, the Leonardo Programme has a budget of €1.75bn, which is helping to encourage UK organisations to work with their counterparts abroad. In what is expected to be another challenging year for employers in the UK automotive sector, S&B’s Chief Executive, Jon Winter, claims that the exchange initiative will bring many benefits to the Academy and its apprentices: “In a world of global automotive brands, it’s important for our learners to understand the international context of the industry they have chosen to make their career. This new exchange programme will enable apprentices and Academy staff alike to achieve a better understanding of the challenges and opportunities within the automotive arena in Europe. With the Academy’s influence also extending to the USA and Asia, there’s every possibility that this initiative could move further afield in the future.” Continued Winter: “The need for skilled technicians across the world is on the increase and we actively encourage our apprentices to look at broader horizons during their training. Many of them have already learned the phrase ‘Vorsprung durch Gelehrtheit’, quite simply, ‘Advancement through learning.” In the 2010/11 academic year, S&B doubled the number of successful Apprenticeships over the previous year with some 350 apprentices graduating from the Academy. At the same time, achievement levels reached an all-time high with an overall success rate of 85%. For those learners on the Advanced Apprenticeship three-year programme, success rates were even higher, at over 98%. PHOTO CAPTION: As part of their exchange visit, S&B Automotive Academy arranged for the German apprentices to visit Hampshire bus operator, Bluestar, at its Barton Park depot. The students are pictured with S&B’s Andy West (3rd right) and Steve Prewett, Bluestar’s Area Engineering Manager (2nd right). Ends http://www.sandbaa.com
An orchestral work by the Pet Shop Boys about the life of wartime codebreaker Alan Turing is to have its world premiere at this year's BBC Proms.
The US Food and Drug Administration (FDA) wants minimum age restrictions and health warnings on e-cigarettes.
A nurse in the Republic of Ireland who admitted taping a patient's mouth to keep him quiet has been given the Probation Act.