"What really gets me," my friend Holly says, "is the way I begin to
spontaneously lactate whenever I hear a baby cry." She fiddles with her nursing bra, grins, and hitches baby Jason (fondly known as "Ace") up a bit higher on her lap. "In
the weeks since my son was born, simply hearing a whimper in the
supermarket from some random baby makes
my milk come down immediately. It's just one more reminder that my body's not my own for a while. Not a bad thing, just...
weird, you know?"
Oxytocin is responsible not only for Holly's lactation but for the feelings she has toward Jason. "Oh. My. God," Holly effuses when I ask her how she feels about her new son. "The way I feel about Ace? It's impossible to describe, but I'll try." She pauses to gaze adoringly into Jason's clear blue eyes. "Remember the butterflies you used to feel when you were first infatuated with your first boyfriend? It's like that, but it's wrapped up in deep, primal emotions that don't even have names. You could call it love, but that's such an inadequate little nothing of a word to describe how I feel about this child. It's like..." Holly casts about for the right word and looks up, intense. "It's like a romance, you know? I had an episiotomy, I haven't slept in weeks, I'm exhausted all the time, but it just doesn't matter. I feel as though I'm in this constant warm bath of emotions, like I'm floating in bliss. No matter how tired I am, I can't get enough of the way he looks when he sleeps. I watch him for hours. And the way he smells. The top of his head, you know? Milky-sweet, like fresh-baked bread with honey on top." Holly gets a dreamy, faraway look in her eyes as she inhales her son's scent. "I'd know his smell anywhere. Give me a hundred baby heads to sniff, and I'd know Ace's. This kid is the love of my life."
As I listen to Holly I smile. Can a simple chemical be responsible for such a tender torrent of emotions? Well, yes and no. Holly is obviously a well-adjusted woman who is blessed with a supportive, loving husband and a secure environment. She has no history of mental illness, and postpartum depression didn't trouble her mother or either of her sisters after they gave birth. It's reasonable to assume that Holly's living the gold standard of the "nurture" end of the "nature/nurture" dichotomy. But I'm intrigued by the "nature" angle, and oxytocin plays an enormous part in the love story between Holly and Jason. As I watch her cuddle and coo over her son, I realize I'm watching an ancient dance cleverly choreographed by evolution. Oxytocin is the music. It's the ecstatic hormonal soundtrack to every love story, maternal and otherwise, ever experienced.
In the last trimester of pregnancy, the human brain begins to secrete large amounts of oxytocin. Many women reminisce fondly about their final trimesters; despite memory lapses (also caused by oxytocin) and the inevitable weight gain, the increase of oxytocin creates a profound sense of well-being in most women during this part of pregnancy. Large numbers of oxytocin receptors are present in the uterus. The body begins labor by producing copious amounts of oxytocin, which signals the uterus to contract and expel the baby. After childbirth, oxytocin levels stay extremely high for several days, enabling the uterus to contract to nearly its pre-birth size and triggering lactation. Oxytocin has both mood-elevating and amnesiac qualities, which researchers believe combine to help women "forget" the pain of childbirth in order to attempt the ordeal all over again. Oxytocin bonds a mother to her child, and when levels are highest (during pregnancy and post-partum), the hormone elicits the single-minded devotion my friend Holly is currently feeling toward her son.
Oxytocin has been dubbed "the cuddle chemical" by zoologists who artificially raised the levels in goats and found that they exhibited the same behaviors as human mothers exhibit toward their newborn babies. Marijuana has been found to stimulate production of oxytocin, and some experts believe that smoking a little pot can be extremely beneficial to a flagging sex drive, particularly for women. Oxytocin is responsible for the uterine contractions that accompany menstruation and cause the expulsion of the uterine lining. As important as oxytocin is in the birth and menstrual process, its role in the non-procreative aspect of sex can't be overstated. Oxytocin is not simply released during orgasm, it seems to actually cause orgasm. At normal bodily levels, oxytocin encourages a mild underlying desire to kiss, nuzzle, and cuddle one's lover. Once the cuddling begins, oxytocin levels steadily rise, and the hormone stimulates the smooth muscles and sensitizes the nerves in erogenous zones such as the earlobes, the neck, and of course the genitals. As arousal builds and becomes more intense, production of oxytocin snowballs. Research suggests that oxytocin causes the nerves in the genitals to fire spontaneously, causing orgasm. Men's oxytocin levels have been found to quintuple during orgasm, but women's levels skyrocket. Women require more oxytocin to acheive orgasm, and the brain generously complies; because their brains are quite literally drenched in the chemical during peak sexual arousal, many women are able to achieve multiple and full body orgasms.
Oxytocin is unique among hormones in that its production can be triggered not only by physical but by emotional cues. The glance of a lover, the cry of a baby, or a certain gesture can all generate a flood of oxytocin. Butterflies in the tummy? Oxytocin. That warm, buttery feeling you get when you remember the fabulous sex you had on your honeymoon? Also oxytocin. Not surprisingly, it's responsible for a great deal of the bonding that goes on in a relationship. Because women produce such a massive overload of oxytocin during sex, it's thought to be the reason that women tend to bond more strongly and let go with greater difficulty once a relationship has progressed to a sexual dimension. That's not to say that men don't benefit from oxytocin; far from it. Though they don't rise to nearly the stratospheric heights as postpartum women enjoy, oxytocin levels in men do increase significantly when they hold and interact with their newborn children.
Oxytocin has other benefits as well. Healthy levels have been proven to reduce stress, regulate sleep patterns, and contribute to a general sense of well-being in both women and men. Stress has been proven to increase prolactin levels in women, a hormone that has been linked to breast cancer, brain tumors, and leukemia. Oxytocin regulates the body's production of prolactin, thereby decreasing one's risk of cancer. Interestingly, celibate women have a markedly higher risk of breast cancer than do women with active sex lives, even sexually active women who don't have early or multiple pregnancies (which have been proven to decrease breast cancer risk). Regular orgasms help to regulate oxytocin, as do intimate acts of cuddling and kissing. What a bonus. Good sex isn't just fun - it may actually help prevent cancer! It's also a natural anti-psychotic, and doctors have found that lithium actually regulates oxytocin production. Some forms of obsessive-compulsive disorder have been linked to oxytocin dysfunction.
Current research points to the benefits of oxytocin in the treatment of many kinds of addictions, particularly heroin and cocaine withdrawal. In rats, intravenous self-administration of both heroin and cocaine was significantly decreased when the rats were treated with oxytocin. Oxytocin also regulates appetite through receptors in the brain, inhibiting compulsive eating and preventing obesity. It's a natural antibiotic, and plays a role in fighting uterine infections. Finally, oxytocin's amnesiac qualities are essential in the necessary meltdown of old information in order to make room for new memory storage.
The human brain is a model of efficiency, and whenever possible it reuses convenient neural pathways. It makes perfect sense, therefore, that a woman would feel emotions akin to "romantic" toward her baby - the same neurological territory is utilized for bonding with a child and lovemaking alike. Breastfeeding causes oxytocin levels to rise so high that many women report experiencing orgasm-like sensations while nursing. It's all wrapped up in the same bundle of emotions and nerves and hormones. It's all part of the same messy, wonderful, oxytocin-fueled waltz.
Sources:
Diane Ackerman. A Natural History of Love. New York: Random House, 1994.
"The Medical Need for Orgasms in Women". © Copyright 2001 - 2002 Artists Cooperative Groove Union U.A. Amsterdam, The Netherlands.
Susan E. Barker. 'The Cuddle Hormone’: Research links oxytocin and socio-sexual behaviors. http://www.oxytocin.org/cuddle-hormone/index.html
Linda Dopierala. Love, Neurochemistry, and Chocolate: A Word from Cupid, PH.D. CyberHealth #21, February, 1999. http://www.antiaging.com/cyberhealth/CyberHealth_21.html