Health around the time of first birth matters for future fertility

Evidence from Norway indicates that chronic health problems are just one of the factors liable to influence individual fertility. Øystein Kravdal, Emily Grundy, and Rannveig K. Hart argue that health issues during pregnancy, a difficult delivery, or a particularly challenging newborn are also associated with reduced subsequent childbearing. 

Why it is plausible that health affects fertility

Mental or physical health problems are related to fertility intentions, childlessness and birth rates (e.g., Lazzari and Beaujouan 2025; Liu et al. 2024; Kravdal, Flatø and Torvik 2025). While, to some extent, such relationships are a result of joint determinants of health and fertility that have not been adequately controlled for, they may also reflect effects of health on fertility through a variety of causal pathways. For example, some chronic and severe health problems may adversely affect education and income, with implications for partnership formation and dissolution, and for a couple’s interest in having children.

Women and men with serious health issues may fear that having a child, or an additional child, would not be a joyful experience, that they would not be good enough parents, or that the strains of parenthood could make their condition worse. Additionally, there may be effects on fecundity and even on the effective use of contraception.

Even for individuals in good mental and physical health, childbearing can be a daunting experience. Some women experience particularly challenging pregnancies with, for example, severe nausea, health risks due to eclampsia, particularly difficult deliveries, or adverse mental or physical postnatal implications even after a relatively normal pregnancy and delivery. The latter include, for example, postnatal depression, pelvic pain, and perineal tears. These women and their partners may be less interested than others in having an additional child: even short-lived mental and physical health problems may be perceived as heavy burdens, and women may not want to take the risk of assuming them a second time. Some may not be physically able to have more children either.

Similarly, while it is often exhausting to care for very young children, some infants are more challenging for parents than others, for example because of their sleep patterns or colic. These issues may persist for several months, or even years, sometimes leading to health problems for the parents themselves. In such situations, some parents may not be very eager to have an additional child, who may affect them in the same way. 

New empirical evidence

Two studies based on nationwide Norwegian register data (Grundy and Kravdal 2025) and on the large Mother, Father and Child survey with added register data (Kravdal, Grundy and Hart 2026) provide evidence for these hypotheses. The latter investigation was based on information about health status around the time of the first birth for about 37,000 women, and around the time of the second birth for about 29,000. It was shown, for example, that mothers who experienced nausea in their first pregnancy were less likely than others to ever have a second child, and they also waited longer if they had one (see Table 1). Women who had pre-eclampsia or (more rarely) eclampsia in their second pregnancy had a reduced probability of progressing to a third birth, as did those who were on sick leave after week 30 of the second pregnancy. 

Furthermore, second- and third-birth probabilities were substantially reduced among women whose previous birth was difficult, as indicated by an emergency caesarean section, and more markedly so among those who had a planned caesarean section (but not when performed for a breech presentation). This situation may signal problems in pregnancy or underlying health problems not captured by other covariates. (The link between delivery mode and second births was investigated thoroughly in Grundy and Kravdal 2025.) Additionally, the probability of having a second child was low among women who had postnatal depression after the first birth or whose first child had colic or slept poorly. Sleep problems were also related to a reduced third-birth probability.  

Certain chronic somatic or mental health problems experienced by the mother or father before the most recent previous pregnancy were also associated with the probability of having additional children (not shown in the table).  

The value of this research

How useful is such knowledge about associations between health and fertility, which may partly reflect causal effects? In principle, it may help us predict the fertility implications of certain types of health deterioration or improvement. Having a more reasonable picture of future fertility levels may in turn be valuable from a planning perspective and for political discussions. Current evidence suggests that the apparent rise in mental disorders among young Norwegians in recent years – and the possible continuation of this trend – has had and will have a modest impact on the national fertility level (Kravdal, Flatø and Torvik 2025). However, it is also useful to be aware of a lack of aggregate-level implications, and there may be other implications relating to other settings and other types of health changes. 

Clearly, when steps are taken to improve the prevention or treatment of various diseases, or increase the quality of patient care, better health and well-being is a goal in itself. However, the evidence referred to above indicates that there may be spin-offs in the form of higher fertility. This means that, if there is concern about low fertility (Kravdal 2025), attempts to prevent or cure diseases, or to make life easier for individuals with chronic or temporary health problems – including during pregnancy and for some time after birth – may serve a dual purpose. This is in line with the conclusions of a recent White Paper to the Norwegian government about the causes and consequences of low fertility (NOU 2026). 

References

Grundy, Emily, and Øystein Kravdal. 2025. “Mode of delivery of the first child and progression to a second birth in Norway.” Population-E 80 (3-4), 381-404. https://shs.cairn.info/journal-population-2021-0-page-381?lang=en

Kravdal, Øystein. 2025. “Should we be concerned about low fertility? A discussion of six possible arguments.”  Demographic Research 53(14), 373-418. https://doi.org/10.4054/DemRes.2025.53.14

Kravdal, Øystein, Martin Flatø, and Fartein A. Torvik. 2025. “Fertility among Norwegian women and men with mental disorders.” European Journal of Population 41 (1): 17. https://doi.org/10.1007/s10680-025-09739-5

Kravdal, Øystein, Emily Grundy, and Rannveig K. Hart. 2026. “Health influences in second- and third-birth probabilities in Norway”. Population and Development Review. http://doi.org/10.1111/padr.70066

Lazzari, Ester, and Éva Beaujouan. 2025. “Self-assessed physical and mental health and fertility expectations of men and women across the life course.” Demography 62 (2): 543-569.https://doi.org/10.1215/00703370-11873109

Liu, Aoxing, Evelina T. Akimova, Xuejie Ding, Sakari Jukarainen, Pekka Vartiainen, Tuomo Kiiskinen, et al. 2024. “Evidence from Finland and Sweden on the relationship between early-life diseases and lifetime childlessness in men and women.” Nature Human Behaviour 8 (2): 276-287. https://doi.org/10.1038/s41562-023-01763-x

NOU 2026. “Policy for new generations – Causes, consequences and measures related to low birth rates. English summary”. NOU 2026:2. Oslo: Ministry of Families and Children.