They are meant to bring comfort, encouragement and snacks, but for some women, having their partner around for childbirth might make a tough time worse.

Hints that a partner’s presence may not be all good have emerged from work by psychologists who found that women who steered clear of close relationships felt more pain when accompanied by their other halves.

The scientists did not intrude on women in labour, nor attempt to reconstruct the act in the lab. Instead they assembled a group of 39 heterosexual women and inflicted instant but tolerable pain by firing a laser at one of their fingers.

During 90 minute sessions, for which they received £30, the women were asked to rate the intensity of pain they felt from the pin-prick laser pulses when their partner was in the room. At the same time, the scientists recorded the women’s brain activity from an elastic cap fitted with electrodes.

Before the study, the researchers gave the women questionnaires to assess what is called their adult attachment style, a measure of whether they sought or avoided closeness in relationships. Katerina Fotopoulou, director of the London Neuropsychoanalysis Centre at UCL, said that when they compared the results, those who needed less emotional intimacy in their relationships felt more pain when their partners were around. Their brain activity appeared to confirm the feelings, she said.

The presence of a partner had no significant effect, good or bad, on the pain felt by women who sought intimacy from their relationships, according to their report in Social Cognitive and Affective Neuroscience.

Fotopoulou said the study results challenged the assumption that people felt better if they had a loving partner along when they faced a painful medical operation. “Depending on how they relate to other people, for some women it’s worse. They might still prefer to have their partner there, but they perceive the pain to be worse,” she said.

The researchers are not sure how to explain their results, but Fotopoulou believes that women who are less trusting of relationships might not feel comfortable exposing themselves in such a vulnerable position. “We recommend that health professionals ask their patients rather than assume the kind of social support they want. People know what they prefer,” she said.