Researchers in one 2012 study found that couples in the first stages of romantic attachment had significantly higher levels of oxytocin than their unattached counterparts.

But oxytocin is tied to more than just new love. It’s also released during sexual activity and linked to the intensity of orgasms.

One 2013 review summarized all of oxytocin’s possible relationship-enhancing effects. Some of these include:

  • trust
  • gazing
  • empathy
  • positive relationship memories
  • fidelity
  • positive communication
  • processing of bonding cues

Oxytocin is a hormone that acts as a neurotransmitter. It plays an important role in reproduction.

In females, the hormone triggers labor and the release of breastmilk. In males, oxytocin helps move sperm.

Oxytocin a naturally occurring hormone. It’s produced by the hypothalamus — a small region at the base of your brain — and secreted by the nearby pituitary gland.

Oxytocin, dopamine, and serotonin are often referred to as our “happy hormones.”

When you’re attracted to another person, your brain releases dopamine, your serotonin levels increase, and oxytocin is produced. This causes you to feel a surge of positive emotion.

One review of research suggests that oxytocin has a positive impact on social behaviors related to:

  • relaxation
  • trust
  • overall psychological stability

The hormone has also been shown to decrease stress and anxiety levels when released into certain parts of the brain.

Oxytocin may help your body adapt to a number of different emotional and social situations.

Intranasal oxytocin has been directly linked to enhanced communication between romantic partners — particularly during arguments.

Research from 2010 also shows that intranasal oxytocin may help people with autism better understand and respond to social cues.

Oxytocin plays several important roles in motherhood.

Labor

The hormone signals the uterus to contract, beginning labor. It helps move the process along by increasing the production of related hormones. After delivery, it helps the uterus return to its previous size.

Breastfeeding

When a baby latches on its mother’s breast, it triggers a release of oxytocin. This signals the body to let down milk for the baby.

Bonding

Human and animal studies on the effects of oxytocin on the mother-child bond have found that mothers with higher levels are more likely to engage in affectionate parenting behaviors, including:

  • frequent checking in on baby
  • affectionate touch
  • singing or speaking to baby in certain way
  • grooming and bathing behaviors

Some research suggests that babies who receive this type of parenting experience a boost of oxytocin that makes them seek more contact with their mother, further strengthening their bond.

These effects aren’t limited to biological mothers. Researchers in one 2014 study found that oxytocin has a similar effect in foster mothers and adoptive parents.

There’s evidence that parenthood stimulates the release of oxytocin in fathers, too.

One 2010 study found that specific types of interaction between father and baby led to higher oxytocin levels. This includes directing the baby’s attention toward certain objects and encouraging the baby to explore.

The link between oxytocin and fidelity may begin with the hormone’s ability to make males view their partners as more attractive than other familiar and unfamiliar females.

Research from 2012 suggests that the hormone may influence males to keep a greater social distance from attractive female strangers.

This may be due to oxytocin’s influence on reward pathways. Engaging in social or sexual contact with your romantic partner may increase your oxytocin levels, creating a behavior loop.

The more time you spend with your partner, the more oxytocin you produce; the more oxytocin you produce, the more you may desire your partner.

One 2014 animal study found that treatment with oxytocin reduced behaviors associated with infidelity, particularly in females who preferred to interact socially with their male partner instead of strangers of the opposite sex. It’s thought that oxytocin decreases the novelty of interacting with a stranger.

Oxytocin affects males and females differently, especially in social contexts.

This may be because the hormone acts differently in the male and female amygdala. This is the portion of your brain responsible for emotion, motivation, and reward.

For example, oxytocin may factor into how females identify who to befriend and how to tend to those relationships. The hormone may play a role in the way males identify competitive relationships and navigate the fight-or-flight response.

Oxytocin may be injected to induce or improve contractions during labor. It may also be used to reduce bleeding after childbirth or abortion.

A 2017 study found that oxytocin may help treat autism and other developmental and psychiatric conditions that impair social interaction.

It’s being explored as a possible treatment for postpartum depression, though one study found that synthetic oxytocin may actually increase the risk for postpartum depression and anxiety disorders.

Research on oxytocin as a possible treatment for alcohol and substance abuse disorders is ongoing.

Although oxytocin can enhance bonding, it may also encourage favoritism and prejudice. This can lead to the formation of “in” groups and “out” groups.

The hormone has also been linked to feelings of envy and dishonesty. More research is needed to fully understand these implications.

It isn’t clear why its effects vary in nature or who may be more likely to experience negative effects. This may depend on other factors, such as underlying psychiatric disorders.

Although it has a demonstrated role in many of the good things that we feel and experience, oxytocin’s role in human behavior is far more complex. More research is needed to understand what this powerful hormone can do.