Flow of participants, sample characteristics, compliance, and follow-up
In 10 months of recruiting, we assessed 1163 women as potentially eligible by chart review and asked them if a research assistant could provide them with a detailed explanation of the study and further assess their eligibility. Of the 958 (82%) women who were assessed, 276 (28%) were not eligible, usually because they were unavailable at one of the data collection times (n=49), were discharged from hospital too soon to arrange a sleep intervention nurse to visit (n=39), or because of a language barrier (n=39). Of 682 eligible women, 246 (36%) agreed to participate and were randomised; 123 women to each group (figure). Of the 436 (64%) women who declined enrolment, 288 (40%) stated they were not interested and 217 (30%) thought they would be too busy in the early postpartum to participate.
Table 1 shows characteristics of the participants. Caesarean birth rates were higher in the usual care group (46%) than in the intervention group (35%). Longer lengths of stay for women who experienced caesarean delivery allowed for greater opportunity for recruitment of those women to the trial, resulting in a higher rate of caesarean delivery in our study than in the general postpartum population. The intervention and usual care groups were similar on all other baseline and demographic variables. Mothers had a mean age of 32 years, most had a partner (97%), and most had post-secondary education (90%). The sample was racially diverse, with women identifying themselves as Asian (20%), black (7%), Hispanic (3%), and multiracial (1%).
Table 1 Baseline characteristics of primiparous women and their infants randomised to sleep intervention or usual care. Figures are numbers (percentage) unless stated otherwise
All but seven women (n=239, 97%) received the sleep intervention while still in hospital. The seven (3%) women who were unable to do so received the intervention over the phone at home (n=3), the booklet (n=3), or a combination of the two (n=1). Reaching women for postpartum phone calls required multiple attempts and coordination with their infant care giving activities. Of the women in the intervention group, 78 (63%) received three postpartum phone calls, and 23 (19%) received two phone calls before determination of outcomes at six weeks, giving a sleep intervention group mean of 2.38 (SD 0.95) calls. Of the women in the usual care group, 70 (57%) received three phone calls to maintain rapport, resulting in a usual care group mean of 2.36 (SD 0.91) calls.
All women who completed any outcome measures at six or 12 weeks were included in analysis. At follow-up times when actigraphy data were lost because of file corruption (31 (7.4%) baby files and 37 (8.9%) maternal files) we substituted data from the sleep diary. Sleep outcomes were completed at one or both of six and 12 weeks postpartum for 215 of 246 (87%) women (110/123 intervention and 105/123 usual care). Longitudinal mixed model analyses indicated no significant differences between groups on any of the primary, secondary, or other outcomes (table 2). The estimated mean difference in maternal nocturnal sleep between the sleep intervention and usual care groups was 5.97 minutes (95% confidence interval −7.55 to 19.5 minutes; P=0.39). At 12 weeks postpartum, 71 (69%) women in the intervention group and 66 (66%) in the usual care group were exclusively breast feeding (relative risk of exclusive breast feeding 1.04 (0.86 to 1.26; P=0.66).
Table 2 Models for outcomes related to sleep, fatigue, subjective sleep disturbance, and postpartum depression in primiparous women and their infants randomised to sleep intervention or usual care and in all women over time
Tables 3 and 4
show median scores related to all maternal outcomes, and table 5 shows mean scores related to all infant outcomes. With a similar longitudinal model, but not including treatment group, there were no differences in any outcomes noted based on the specific nurse delivering the intervention or the number of phone calls received.
Table 3 Maternal sleep and subjective sleep disturbance outcomes at 6 and 12 weeks in primiparous women and their infants randomised to sleep intervention or usual care. Figures are medians (interquartile range)
Table 4 Fatigue, postpartum depression, and subjective sleep disturbance outcomes at 6 and 12 weeks in primiparous women and their infants randomised to sleep intervention or usual care. Figures are means (SD)
Table 5 Infant sleep outcomes at 6 and 12 weeks in babies of primiparous women randomised to sleep intervention or usual care
Use of sleep advice, co-intervention, acceptability of trial
At 12 weeks, 103 (84%) women in each group responded to the final questionnaire related to other sources of sleep information, their views on participation in the trial, and, for women in the intervention group, their use of the sleep advice and strategies given.
An equal number of women in the intervention (n=63, 61%) and usual care groups (n=63, 61%) sought information related to maternal or infant sleep from other sources. Among all the participants, 85 (41%) women consulted books, 73 (35%) women accessed the internet, and 72 (35%) women asked other mothers for advice. Only 29 (14%) women asked a physician, and nine (4%) women asked another healthcare professional for information on sleep.
More women in the intervention group (n=91, 88%) than in the usual care group (n=76, 74%) said that they liked their contacts with study staff. More women in the usual care group (n=81, 79%) than in the intervention group (n=68, 66%) said that they liked the exercise of keeping a sleep diary. Most women (n=86, 83%) in the intervention group liked receiving information about sleep from the study nurse and also liked the written material they received (n=81, 79%). Only four women in each group (3.9%) indicated they would probably not participate in the study if they had to do it over again.
It was not the intention of the intervention that each piece of advice be used by every woman; rather we expected that each woman would try many, but not all of the tips, depending on her unique needs and abilities. Each of the suggested strategies to improve infant sleep was reported as used by at least 79% of the women (range n=82-100, 79-97%) in the intervention group with the exception of advice to avoid letting the baby sleep during feedings (n=69, 67%) and to involve partners and other family members in implementing the sleep advice (n=76, 74%). Fewer than half of the women (range n=33-49, 32-48%) used advice related to use of cigarettes, alcohol, drugs for postpartum pain, changing negative thoughts about sleep, and turning down the volume on baby monitors. Many women probably reported not using these tips because these sleep inhibitors were not relevant to their lives—for example, they might not smoke or have negative thoughts about sleep. At least 60% of women (range 64-96, 62-93%) used other advice related to maternal sleep, with the exception of the strategies of progressive muscle relaxation (n=25, 24%), deep breathing (n=37, 36%), writing down worries before sleep (n=30, 29%), and avoiding computer and television use before bedtime (33, 32%).