The most ambitious discussions about having second children occur during a date night, in between the first and second bottle of wine – where the short and long-term impacts of children peer out from the distant future. Loading These tensions between the short- and long-term impacts of children tap into what social scientists call the stress process model. In this perspective, major life events can increase stress either in the short-term, as an eventful experience, or as a chronic strain, with effects that linger over time. Health researchers show that chronic stress is the most detrimental to health and well-being, contributing to cardiovascular disease, obesity and other major diseases. We are not arguing that children lead to heart disease – we have our Western diets to thank for that – but rather pose the question of whether the birth of first and second children has short or long-term effects on Australian parents’ time pressure and, because of that, mental health. The birth of a first child introduces adults to a new role – that of parent – that comes with expectations about how to allocate time to work or family. Following childbirth, many Australian mothers take a year of parental leave. Some return to work, but others do not.

Most Australian fathers maintain full-time work after children are born, in part to make up for mothers’ employment reductions, but also because Australian parents become more traditional in their gender roles following childbirth. Loading Mothers and fathers are more likely to believe that women should stay home to care for children once they become parents than when they were childless. As a result, the bulk of the childcare falls to mothers. Second (and third) children do not introduce a new role into parents’ lives, but rather increase the demands of the parent role. In theory, parents of second children have developed parenting skills – including how to clean a bottle while rocking a baby, and to never buy expensive dry-clean-only clothes again. These parenting skills may mean that second children bring less time pressure and stress than first children. Our results, however, do not support this claim.

Prior to childbirth, mothers and fathers report similar levels of time pressure. Once the first child is born, time pressure increases for both parents. Yet this effect is substantially larger for mothers than fathers. Second children double parents’ time pressure, further widening the gap between mothers and fathers. Time pressure increased with first and second children for all parents ... working or not. Reducing work to part-time is not a solution. Although we hoped parents’ time pressure would diminish over time – as they gained more skills or kids entered school years, we found that time pressure lingered. We also thought that parents working full-time or those doing most of the housework would be the ones experiencing increased time pressure. Instead, we found that time pressure increased with first and second children for all parents, whether they were working or not. Thus, reducing work to part-time is not a solution to this time-pressure problem. Parents of third children fare no better, indicating that children are not economies of scale. To better understand the health implications of parents’ increased time pressure, we also looked at their mental health. We found that mothers’ mental health improves with first children immediately following birth and remains steady over the next few years. But, with the second child, mothers’ mental health sharply declines and remains low.

The reason: second children intensify mothers’ feelings of time pressure. We showed that if mothers did not have such intense time pressures following second children, their mental health would actually improve with motherhood. Fathers get a mental health boost with their first child, but also see their mental health decline with the second child. But, unlike mothers, fathers’ mental health plateaus over time. Clearly, fathers aren’t facing the same chronic time pressure as mothers over the long-term. So, what does this mean for Australian families and the institutional environment in which they are embedded? First, mothers cannot shoulder the time demands of children alone. Even when they reduce their work time to accommodate children’s demands, their time pressures do not ease. This has important consequences for their mental health. Further, the effects of children on mothers’ time pressure is not short-lived, but rather is a chronic stress that slowly deteriorates their health. As such, maternal time pressure must become a top health priority for practitioners and policymakers. Second, mothers need institutions to share in the care. Collectivising childcare – for example, through school buses, lunch programs and flexible work policies that allow fathers’ involvement – may help improve maternal mental health. Since poor post-partum mental health can lead to poor outcomes for children, it is in the national interest to reduce stressors so that mothers, children and families can thrive. This article originally appeared on The Conversation.