The period following childbirth is stressful for parents and uncontrollable crying is an important cause of this stress. Wolke and colleagues  have consolidated the results of studies across the world in a meta-analysis and show that:
- Crying peaks at around six weeks of age, and then declines sharply over the next three months.
- Bottle or mixed-fed babies cry less than those that are purely breastfed.
- Crying is much more common in some countries (Canada and UK) than others (Denmark and Japan), and this is a robust finding (i.e. replicated across many studies). I don’t suppose that this is the result of lower breastfeeding rates in Denmark and Japan than in Canada or the UK?
What the study does not show is how crying varies within families or by birth order. Nor does there seem to be an effective remedy for the problem. Pilgrim was right, it is not easy being a human, not at the beginning, not in the middle, and certainly not at the end.
— Richard Lilford, CLAHRC WM Director
- Wolke D, Bilgin A, Samara M. Systematic Review and Meta-Analysis: Fussing and Crying Durations and Prevalence of Colic in Infants. J Pediatr. 2017.