A new study suggested that parents are happier during the births of their first and second child, but not as much for the third, due to the fact that parenting is "less novel and exciting" by the time of the third child's birth.    

Findings implied that parents are experiencing childbearing and future planning issues within their partnerships.

Researchers from LSE and Western University, Canada found that children boost the happiness level of their parents, but only for a while. The team analyzed data from surveys conducted in Germany and Britain, and observed that parents feel happier a year before and after the baby is born. This seemed to be true for the second child as well. On the third child, parents inadvertently switched back to their "pre-child happiness level," according to LSE.

The happiness level of parents varied among different ages. Those aged 35 to 49 experienced the highest level of happiness, while those between age 18 and 22 reported a decline in their happiness. A first-born child brought the most happiness, no matter what age the parents were. There was a 50 percent decrease in happiness during the birth of a second child, followed by a total slump by the time the third child is born.

"The arrival of a third child is not associated with an increase in the parents' happiness, but this is not to suggest they are any less loved than their older siblings. Instead, this may reflect that the experience of parenthood is less novel and exciting by the time the third child is born or that a larger family puts extra pressure on the parents' resources. Also, the likelihood of a pregnancy being unplanned may increase with the number of children a woman already has - and this brings its own stresses," Mikko Myrskylä, professor of demography at LSE and Director of the Max Planck Institute for Demographic Research in Rostock, Germany, said in a news release.

Study co-author Rachel Margolis implied that their findings could explain why most people are delaying fertility. Older parents have better financial and education status than younger parents and are also less stressed after the birth of their children. Younger parents, on the other hand, are more prone to post-birth depression.

"The fact that among older and better-educated parents, well-being increases with childbearing, but the young and less-educated parents have flat or even downward happiness trajectories, may explain why postponing fertility has become so common," she said.

Further details of the study were published in the journal Demography.