Oxytocin: The Hormone of Love

Kerstin Unvas-Moberg

This is Part Two of BWI President Cathy Daub's report on the Mid-Pacific Womb Ecology Conference, held in Honolulu, HI in October of 2012.

From a lecture by Kerstin Uvnas-Moberg MD, PhD

Kerstin Uvnas-Moberg began her lecture by describing oxytocin as a highly charged protein that does not pass membranes easily. Thus, it cannot be measured well in saliva or mucous. It is also a neurotransmitter in the brain. The Paraventricular Nucleus (PVN) is a very important oytocin producing site. From the PVN, neurons pass down to the pituitary but also to many other areas of the brain. Thus oxytocin may have psychological effects as well as physical effects like breastfeeding. The important thing is that oxytocin releases in the brain and circulation at the same time.

What triggers oxytocin release? Labor activates nerves from the cervix to the spinal cord and to the brain. Mammary sensory nerves send impulses to the brain for oxytocin release. Skin nerves release oxytocin so touch is very important. The effects cannot be obtained by looking, but rather by touching and being held. In fact more oxytocin is produced when a baby’s hand massages her mother’s breast than by nipple stimulation. This massaging creates a positive cycle where the mother is more interested in her baby and more oxytocin is produced. Babies have an inborn capacity to suckle within one hour of birth. There is a higher rise of oxytocin when the baby is on her mother’s skin right after birth.

Oxytocin is also released from neurons in the brain and leaks out and reaches lots of areas in the brain without even needing nerves so it is acting in many ways. More oxytocin is released in a new mother just by seeing and hearing her baby. Finally, it is interesting that oxytocin triggers its own release, which further triggers other releases.

The mother’s temperature pulses with skin-to-skin contact with her baby. She becomes warm and this helps the babies to relax and open their blood vessels. These babies have better self-regulation one hour later and this becomes a learned response.

Kerstin explained that children who have not had skin-to-skin contact with their mothers at birth and through breastfeeding, exhibit behaviors that are not as closely connected to their mothers as those who have had skin-to-skin contact and this remained true at one year of age. Children were filmed during play interaction one year after birth. Those with mother/baby skin-to-skin contact were more sensitive and interactive as compared to those without mother/baby skin-to-skin contact. In addition, the babies’ ability to handle stress was better than those babies without mother/baby skin-to-skin contact, showing there is a long-term effect.

In the HPA (Hypothalamic Pituitary Axis), oxytocin makes the mother calmer in the amgydala (limbic or emotional brain). Oxytocin neurons pass down to the pituitary to enhance production of prolactin and other substances for breastfeeding. Dr. Moberg also related that the half-life or duration of the substance is stated in the literature as being three minutes but that this is not true. In actuality, oxytocin has a much longer half-life of about 20-30 minutes. Dr. Moberg mentioned that if there is no mother/baby skin-to-skin contact in the first hour after birth – a biological window – later, there would be a need to repeat things more often to get the same effect. Early interaction influences the long term – it is more difficult for mothers and babies to come back to this positive interaction later on.

Obstetrical anesthetics interrupt the natural flow of hormones and have behavioral consequences. Dr. Moberg said that mothers who didn’t have oxytocin release were the mothers whose children didn’t touch their mothers – they received blocks. The mother and baby interacted less efficiently. You could actually calculate if mothers had received blocks – babies had to press twice on mother’s breasts and still less oxytocin was released so the whole system has become less sensitive. In other words, there is a blocking of the whole oxytocin system. This is important because this early interaction influences the long term. We have lost this positive influence to the brain and it leaves mother and baby where stress will have a much greater impact.

Mothers with normal birth have more social babies and both mother and baby are more relaxed. With a cesarean section, there may be no oxytocin release. If a scheduled cesarean, there is no labor to stimulate the release of oxytocin compared to normal vaginal delivery. Four days after birth, a woman normally has oxytocin pulsing releases at 90 second intervals and each time there is a milk ejection release. With a cesarean these nice pulsing releases are absent. So there is a disturbance in oxtytocin release in cesareans. This may be due to lack of skin-to-skin contact. There are no peaks in prolactin levels in cesarean mothers four days after birth so a lack of oxytocin has made prolactin release affected so breastfeeding in cesarean mothers is difficult.

An epidural blocks transmission of nerve impulses in the spinal cord so there is a decrease in oxytocin production during labor. In addition, with an epidural, there is an inhibition in the rise of skin temperature in the infant. When a mother holds her baby, the baby’s skin temperature increases which is a sign of relaxation. You normally see nice skin rising temperature in the first couple days after normal birth, but you don’t see this a couple days later in cesarean mothers. Mothers with decreased oxytocin secretion had higher blood pressure and cortisol levels i.e. increase in stress hormones with decreased ability to relax.

In summary, Dr. Moberg expressed her concern:

In labor, something happens in the regulatory system when there is interference in the natural process and this is especially true if it happens during a sensitive period. There are long-term effects. When you give exogenous oxytocin (Pitocin) to rats, it lowers their blood pressure – and it remains lower for life. Problems with breastfeeding are consistent with the effects of a sensitive period and it is likely that this can have an influences in a negative way for a long time. Low oxytocin levels lead to low breastfeeding and long-term impact.

Dr. Moberg’s new book “The Hormone of Love” will be published in March 2013.