U.S. State Department officials and family planning groups such as Planned Parenthood said they expect Obama to overturn the "Mexico City" policy, first instituted by the Reagan administration.

CNN: Obama may reverse Bush policies on stem cells, drilling, abortion

On questions such as gay marriage, abortion and funding for Planned Parenthood, a family-planning group, Mr Romney, his running-mate Paul Ryan and his party have big electoral weaknesses among women, especially younger ones.

ECONOMIST: The campaign

David Kesterton, parenthood and community project manager at the Family Planning Association, says there are a variety of sensible and practical reasons why men are having children later in life.

BBC: Older fathers: what's behind the trend?