Interaction With an Infant Simulator: Hormonal and Behavioral responses in Mothers and Non-mothers

• In Event: Parents at the Transition to Parenthood

Abstract

Background. The transition to parenthood modifies the mother’s brain anatomy, which is associated with changes in hormonal levels. In earlier studies, key parenting-related hormones such as oxytocin, cortisol, testosterone, and estradiol have been associated with caregiving behavior. But do the hormonal influences on caregiving behavior change across the transition to parenthood? In this study, we investigate the behavioral and hormonal responses to an infant simulator in first-time mothers and non-mothers. By comparing these two groups we can study whether hormonal associations of caretaking behavior might change across the transition to parenthood.

Methods and participants. The participants were 54 first-time mothers (age 29.91) of 6-month-old babies and 63 non-mothers (age 26.32). The study protocol consisted of a lab visit where participants took part in a simulated caregiving task with an infant simulator and provided two saliva samples (one before and one 10 minutes after the interaction situation) to analyze oxytocin, testosterone, cortisol, and estradiol levels. The simulator weighed around 5 kg and resembled a real infant in appearance and vocalizations. The interaction situation was filmed, and the behavior of the participants was analyzed by two coders. The amount of affectionate touch and motherese were analyzed as behavioral measures of caregiving. Non-mothers also provided information about their fertility motivation (i.e., ‘baby fever’) with the Attitude Toward Babies Scale (Brase & Brase, 2012).

Results. Linear mixed models performed separately for each hormone revealed that cortisol levels decreased in both groups in response to the infant simulator interaction (p = .002) but only in mothers lower overall cortisol levels were inversely associated with affectionate touch (p = .035). Lower overall testosterone levels were also associated with greater use of affectionate touch (p = .032). There was no significant oxytocin or estradiol reactivity to the simulator, no differences between the two groups, nor were these hormones associated with behavior. In non-mothers, higher fertility motivation was related to more motherese (p= .001), and lower baseline testosterone level (p = .001).

Conclusions. The infant simulator elicits hormonal reactivity both in mothers and non-mothers. However, the pattern of associations between caregiving behavior and hormonal levels might be partially different in the two groups. Testosterone seems to be inversely related to caregiving behavior as earlier studies have had similar findings. Fertility motivation is widely understudied although being a familiar concept in the media. Our results indicate that women's positive feelings toward infants and motivation to become a mother affect their caretaking behavior in a positive way. It remains unclear whether low testosterone levels in women increases their interest in having babies or vice versa. Together these results encourage using the infant simulator to explore hormonal processes related to the transition to parenthood.

Authors

• Hanneli Sinisalo, Tampereen yliopisto (Tay)
  Presenting Author

• Marian J Bakermans-Kranenburg, ISPA Lisbon

• Mikko Peltola