A Sheffield University study found that married couples with a mother-in-law living nearby have more babies. Records also show these children are less likely to die in infancy, the 'Daily Mail' reported.
Although, the study revealed that grandfathers seem to have less impact on kids, Dr Virpi Lummaa who conducted the study said, "That doesn't mean they don't do anything. It just doesn't translate into better survival of their grandchildren".
The study discussed at the Euroscience 2012 conference in Dublin, involved analysis of 300 years of church records, the most recent of which were from 2000.
The data which was used to track births, marriages and deaths in farming communities in Finland, found that sons and daughters tend to marry younger if their mother was alive. They also had more children, and left smaller gaps between babies.
Dr Lummaa proposed that as the influence was only evident when a mother-in-law lived nearby, the affected families probably benefited from an extra pair of hands, as well as the additional love and attention the children received.
The study said there was little difference between maternal and paternal mothers-in-law, but previous research into African families suggests that a mother's mother provides the greatest benefits.
Age could be a factor here, as men tend to marry later than women, their mothers are also likely to be older, meaning they may be less able to help raise their grandchildren.
Dr Lummaa's work which aims at finding out why women lose the ability to have children when they are still young, while other mammals can reproduce into old age.
Her results back the theory that menopause is nature's way of stopping women from having children, while they are still young enough to become grandmothers.
This allows them to skip the trauma of childbirth and still safeguard their genes, by lavishing their grandchildren with love and attention, the report said.
