Why Babies Cry: A Natural Form of Contraception

Babies keep you up all night so you can't keep it up!

It’s official. Babies conspire to keep us sleep-deprived on purpose. Not only that, but they’re using it as contraception to knock out the competition. A new study by Harvard University has uncovered that maternal fatigue can be interpreted as an infant’s clever strategy to delay the arrival of new brothers and sisters.

That’s right, just when tired Mums are starting to emerge from the 6 month tunnel of torture after a newborn has entered the scene and decimated all semblance of sleep and social life, they bring out the big guns and begin crying for night time feeds in order to thwart you and hubby from getting it on.

Talk about weapons of mass destruction. Apparently babies have been quietly honing this technique through thousands of years of evolution. The theory goes that longer delays between the birth of siblings increases a baby’s survival and so they will often start to wake at night to make a booty call for the breast, just when you’re starting to become fertile again.

According to Professor David Haigh who led the study, “maternal fatigue can be seen as an integral part of an infant’s strategy to extend the inter-birth interval. More frequent and more intense nursing, especially at night, is associated with prolonged infertility.”

And just to add insult to injury, guess who is responsible for this Darwinian gem? The man in your life! Evidence collected from babies with Angelman syndrome suggests that it may be the fathers’ genes that are responsible for this brutal basic instinct.

So next time you get hit up for a bit of loving but just feel too tired, at least you have a revolutionary evolutionary excuse!

Information obtained from Evolution, Medicine and Public Health.