Terrie Inder and her colleagues have put the cat among the pigeons (as we say in England, I guess we are not keen on pigeons).

Her (non-randomized) study suggests that babies who were treated in single rooms had poorer language skills than babies treated in a more traditional unit, with large, multi-patient rooms. Depending on bed availability infants were either admitted to large rooms of 8 beds or so, or single rooms. They followed the babies under 30 weeks gestation out to 2 years of corrected age, 83% of the survivors (n=86) returned for neuro-developmental follow up. I won’t mention the EEG and imaging findings which showed some differences, but rather the 2 year Bayley scores, which were worse in the language domain for babies from single rooms, and motor scores were also somewhat worse.

Single room designs have become the norm for new NICU construction based on data which show an increase in parent satisfaction, an increase in parental presence, and expected reductions in health care associate infections, especially a reduction in patient to patient spread of viral diseases.

This new data should make us reconsider carefully how to optimise the neonatal environment.

One of the possible explanations for this finding is that single rooms tend to be very quiet, and they may be too quiet, with not enough auditory stimulation for the development of the auditory pathways. But perhaps this is not generalisable, in the USA maternity leave is usually 1 month without pay. As I understand it, this may vary by state, but if you have a long stay baby in the NICU, being with the baby a few hours every day and talking to them is extremely difficult to sustain unless you are independently wealthy, or unemployed.

In the NICU where these new data come from, parental visiting was an average of 2 hours a day in the open rooms, and 4 hours a day in the single rooms (in the 3rd and 4th week of hospitalisation). This major increase in visiting time may not be enough to counter the 20 hours of very quiet, undisturbed rest, which we usually think of as a benefit.

In other cultures, mothers are able to spend much longer. Parents in Québec can share a year of parental leave, and for the first half of that can qualify for income from a government supported insurance scheme. It may be that in cultures where the parental leaves are more generous, parents will spend longer with their babies in single room designs, that would be interesting to see.

A commentary in Acta Paediatrica is written by one of the investigators of the Stockholm RCT of Family Centered Care. In that study infants stable enough for intermediate care were randomized, one part of the family care intervention was a single room. I can’t see from that report how long the parents stayed with their infants, and there was no long term follow up.

The thoughtful commentary (Örtenstrand A. The role of single-patient neonatal intensive care unit rooms for preterm infants. Acta Paediatrica. 2014;103(5):462-3) refers to a systematic review that I was not aware of. The SR includes 10 articles, only one of which, the Stockholm study, was an RCT. The others are various observational designs with potential biases, but which suggest a range of benefits of single rooms.

I think it is possible that the effect shown in the study from St Louis is a real effect. I would be a little surprised if the single room was actually quieter than being in utero, so I would guess that it is the nature, rather than the intensity, of the sounds that may be important.

Which brings me back to the issue of the mother’s voice, and the importance of the mother speaking to her baby. Babies born at term recognize certain features of their mother’s voice from very early after their birth, almost certainly because the antenatal experience of the mother’s voice has impacts on the development of central auditory processing. I think this suggests that the potential adverse effects of being in a single room might have to do with reduced exposure to voices, and that maybe we can counter this effect by encouraging mothers to talk to their infants whenever they are present, and to use recordings of the mothers’ voices when they can’t be there.