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First published in Australia’s Parents Pregnancy, Autumn 1999, as “Your Hormones are your Helpers.” This version updated July 2005.
Imagine this—your cat is pregnant, due to give birth around the same time as you are. You have your bags packed for hospital, and are awaiting the first signs of labour with excitement and a little nervousness.
Meanwhile, your cat has been hunting for an out-of-the way place—your sock drawer or laundry basket—where she in unlikely to be disturbed. When you notice, you open the wardrobe door, but she moves again. Intrigued, you notice that your observation, even your presence, seems to disturb the whole process. And, wish as you might to get a glimpse into the mysteries of birth before it is your turn, you wake up the next morning to find her washing four newborn kittens in the linen cupboard.
Why does birth seem so easy for our animal friends when it is so difficult for us? One obvious difference is the altered shape of the pelvis and birth outlet that is caused by our upright stance; our babies need to twist and turn to navigate these unique bends. Even our nearest cousins, the great apes, have a near-straight birth canal.
However, in every other way, human birth is like that of other mammals (animals that suckle their young) and involves the same hormones—the body’s chemical messengers. These hormones, which originate in the deepest and oldest parts of our brain, cause the physical processes of labour and birth, as well as exerting a powerful influence on our emotions and behaviour.
Researchers like French surgeon and natural birth pioneer Michel Odent believe that, if we can be more respectful of our mammalian roots and the hormones that we share, we can have more chance of a straightforward birth ourselves.
Labor and birth involve peak levels of the hormones oxytocin —sometimes called the hormone of love—and prolactin, or the mothering hormone. These two hormones are perhaps best known for their role in breastfeeding. In addition to these, beta-endorphin, the body’s natural pain-killer, and the fight-or-flight hormones adrenaline and noradrenaline (also called epinephrine and norepinephrine) play an important part in the birth process. There are many more hormonal influences on birth that are not well understood.
All mammals seek a safe place to give birth. This “nesting” instinct may be due to an increase in levels of prolactin, sometimes referred to as the nesting hormone. At this stage, as you may have observed with your cat, interference which the nest—or more importantly with the feeling of safety— will stall the beginning of labour.