Oxytocin, often referred to as the love or bonding hormone, is the little bugger of a chemical that not only increases a woman's attachment after sex, but also guides her maternal instincts after childbirth and when breastfeeding. The hormone has long been thought to play an instrumental role in the unique relationship a mother shares with her offspring.
Men also produce the hormone, but it's long been debated as to what sort of bonding powers it has over the gruffer sex. A recent study out of Israel suggests a man's oxytocin levels may actually be on par with their wives/girlfriends during the child rearing process. Researchers drew blood from 80 couples who were raising a six-week old baby and found identical amounts of the bonding chemical in their blood streams. As the child matured to six months, the scientists once again analyzed the levels and found the same result. It seems that a mother and father's oxytocin levels rise together while they watch their wee one grow. Cute. Fall In Or Out Of Love By Taking A Pill
The team noticed a few other things, too. Women have more of a pinching-cheeks-and-cooing kind of an instinct called "affectionate parenting behaviors" while men have what's been categorized as "stimulatory parenting behaviors" i.e. bonding of the rough housing and wrestling variety.
Another interesting tidbit: bonding activities from orgasm to eye contact increase oxytocin levels, which helps to explain why getting intimate with a partner makes you feel more connected. The good news for couples with kids—while sex- or romance-generated oxytocin may beg off in the time period following a child's birth, bonding with your child should help fill the couple-created void. 5 Ways Having Sex Makes A Couple Stronger