The fourth trimester

Recently, two advanced trainee paediatricians of my acquaintance have become first-time mothers in their early 30s and have felt almost overwhelmed by having a demanding newborn baby. These highly capable young women are used to nocturnal sleep deprivation, although when you are on call you can look forward to some rest when your shift ends. But they both described how the lack of sleep drained them of energy and confidence. They felt to blame for their baby’s crying, even though, at an intellectual level they had read and were well aware that many babies cry a lot during their first few weeks of life. They knew of the fourth trimester, a term coined by US paediatrician Harvey Karp referring to the 3 months that babies cry inconsolably every evening. The concept of the fourth trimester is that human babies are born less mature than other animals and may need nurturing as if they were in utero (Fig. 1). The mothers tried swaddling and shushing to soothe their babies as suggested in the world according to Karp. And still the babies cried, and the young mothers felt to blame and struggled to cope. Both young women had husbands who were sympathetic and supportive but who had busy, demanding jobs with responsibilities they could not shirk. One had a grandmother who was no longer in paid employment and was willing and able to drop everything and look after the baby during the day while the baby’s mother caught up on much-needed sleep. The other’s parents were overseas, so her feelings of helplessness and hopelessness were compounded by her sense of isolation. Both grandmothers reassured their daughters that they were not to blame, but the mother who could catch up on sleep was better able to accept the reassurance. One mother took the intellectual response you might expect from a highly educated woman and read everything she could about crying babies. The result was that she discovered PURPLE crying, which was new to me but apparently is the period when a baby cries more than any other time. This is a colourful way of formulating what the literature already describes, that babies cry a lot in the first 9 weeks after birth; then for the vast majority, the crying gradually settles. This can be reassuring to know, but your baby is still crying. One mother said it helped when she came to realise that the fourth trimester is a period of rapid adjustment not only for the mother but also for the baby. Another response is the medical one: if a baby cries, there must be a medical explanation. This drives parents to seek medical help. Doctors never like to admit they do not have a quick medical fix to a problem, and pharmaceutical companies are always happy to provide the fix in the form of a marketable medication, even if the evidence shows it is usually ineffective and possibly harmful. So before long the persistently crying baby has a diagnosis of infantile colic, soon followed by another diagnosis of infantile reflux, and has been started on a proton-pump inhibitor. Reflux is a genuine entity but is over-diagnosed and overtreated. Paediatricians are of course keen to breastfeed and are easy prey to advise about the importance of exclusive breastfeeding. Many people will tell them that even a drop of cows milk formula increases their infant’s risk of allergy. As a result, they do not complement their infant’s breastfeeds with formula top-ups, even when the infant is hungry and not putting on weight. There is no evidence to support this strongly held belief that early exposure to cows milk promotes allergy. A randomised controlled trial comparing early introduction of allergenic foods at 3 months with delayed introduction at 6 months found no difference for cows milk, although the overall incidence of food allergy was lower in the early introduction group. Furthermore, there is strong evidence showing early introduction of peanuts reduces the incidence of peanut allergy in children from atopic families, and similarly early egg introduction reduces the risk of egg allergy. The result of the well-intentioned advice on breastfeeding from experts is that anxious mothers do not top up their hungry babies, and the result can be that the exhausted mother’s milk supply is compromised, resulting in failure to thrive from failure to feed. Young first-time parents often think they will mould their infant to be a wonderful moral human being who will reflect their parents’ values. After a while, they come to the realisation that the infant is born with her or his own personality, and it is the parents who are being moulded by this extraordinary little human being. Each baby is born with his or her Fig. 1 Two mothers with crying babies and one in a walking frame, comparing the human infant’s helplessness with the self-sufficiency of newborn animals. (Engraving by P. Galle, c1563.) doi:10.1111/jpc.14257