Is there a crying curve in the first months of life?

In summary, the evidence doesn't really support the existence of a peak or a meaningful curve of cry durations in the first 12 weeks of life. Also, the concept of a crying curve isn't clinically useful. It doesn't help in our work with parents of babies who cry and fuss alot in the first 16 weeks and is best avoided.

Two systematic reviews examine the concept of an infant crying curve in the first months of life, which was put forward by paediatrician Dr T. Berry Brazelton in 1962.

Study 1

A 2017 systematic review (which synthesises all existing studies) and meta-analysis of crying durations in developed countries selected 28 studies, which used parent-completed diary-based studies up until 12 weeks of age. This analysis showed that babies cry on average two hours a week from birth to six weeks (in a plateau effect), decreasing to a little over an hour a day at 10-12 weeks, and then generally settling by about 16 weeks. The study also demonstrates that crying durations are modified by culturally-determined infant-care practices.

Study 2

In 2022, another systematic review and meta-analysis, which selected 57 studies from 17 countries, examined crying durations in the first twelve months of life. Most studies focussed on the five to six week period and most of the data came from the UK, Canada and the US. The authors conclude that

• Durations of reported infant crying are highly variable

• No consistent evidence for difference in cry-fuss durations related to feeding method

• There is country-related variability and also crying varies as a result of impact of environmental factors, such as parent responsiveness

• There could be flattened elevation of crying durations at four weeks which persists in plateua to eight weeks, but

  • Parent reports of crying (e.g. with Barr's Baby diary) are different to actual durations

  • Any initial rise and subsequent decay in crying durations not as dramatic as previously depicted, consistent with Wolke et al 2017, which proposes there is no crying curve

  • IMPORTANTLY most studies on crying durations focus on infants aged five or six weeks and their elevated crying durations. This has happened because researchers worked from the assumption (Brazelton 1962) that there was a crying peak at five to six weeks

• Even after the first 8 weeks of life (which is characterised by highest crying durations), babies have mean cry durations of 40-45 minutes over a 24-hour period

• Crying remains substantial throughout the first year of life

• Wessel critiera may capture infants in the upper quartiles in some countries, but not in others.

Is Wessel's Rule of Three a useful way of diagnosing excessive infant crying?

Paediatrician Morris Wessel developed the Rule of Three infant crying criteria in 1954, defining 'colic' as crying for three hours a day, three days a week, for three weeks in a row.

However, researchers have concluded that determining if an infant falls into the category of excessive crying by applying the Wessel's criteria is not clinically meaningful. Even the modified Wessel's criteria, which drops the three weeks in a row requirement, doesn't help parents or clinicans. Whilst the Wessel's criteria may have some application in research, in clinical practice Wessel's criteria only capture the upper end of infant cry-fuss problems presented by families.

From the NDC perspective, any family who presents concerned about their baby's crying behaviours requires careful assessment and intervention with the Possums or NDC 5-domain approach, so that they are equipped to experiment with multiple strategies which aim to dial their baby down.

These families also require opportunity to learn about strategies which support their own psychological resilience in this difficult situation, drawn from Acceptance and Commitment Therapy, and Compassionate Mind Training (self-compassion).

References

Vermillet A-Q, Tolboll K, Mizan SL, Skewes JC, Parsons CE. Crying in the first 12 months of life: a systematic review and meta-analysis of cross-country parent-reported data and modeling of the "cry curve". Child Development. 2022.

Wolke D, Bilgin A, Samara M. Systematic review and meta-analysis: fussing and crying durations and prevalence of colic in infants. Journal of Pedatrics. 2017;185:55-61.