Although 37 weeks is traditionally considered term, evidence has emerged that early term (ET) infants, defined as infants born 37+0 to 38+6 weeks, are more immature than term infants born at 39+0 to 41+6 weeks.1,2 Literature regarding ET infants has demonstrated that they have higher rates of respiratory distress, admission to Neonatal Intensive Care Unit (NICU), length of hospital stay, and hospital readmission than their term counterparts.3–7 Recent reports reveal that the long-term consequences of ET births include increased childhood asthma, cardiovascular disease, diabetes and obesity, health care-related costs during early childhood, need for early intervention, decreased cognitive scores, speech and/or language delay, and worse school performance at 7 years of age than their peers.6,8–15
The neurological immaturity of these infants also extends to difficulties in breastfeeding.4,6,16–18 There is, however, limited literature regarding the effects of ET birth on exclusive breastfeeding and no studies that examined breastfeeding intensity. The purpose of this study was to prospectively study breastfeeding exclusivity and breastfeeding intensity of ET infants compared with term infants during their postpartum hospitalization and the first month of life.
Materials and Methods
This was a prospective cohort study conducted from April 2013 to July 2014 at the Hadassah Medical Center, a major teaching and referral center in Israel. During the study period, there were no differences in hospital policies for ET or term infants, and there were a total of 9,015 births. There is no Baby Friendly Hospital in Israel. The study composed of a convenience sample. A power analysis was performed for sample size, which was calculated to achieve a power of 0.80 for α of 0.05. Due to the prospective design of the study, the intention was to enroll 207 ET infants and 158 term infants to account for an attrition of 30% at 1 month.
Inclusion criteria included singleton newborns born between 37+0 and 41+6 weeks, whose mothers intended to breastfeed, who did not need admission to the NICU, were appropriate for gestational age, and were born to mothers aged 18–45 years. Exclusion criteria were any breastfeeding contraindications (e.g., HIV, Human T-cell lymphotropic virus [HTLV] HTLV-1, HTLV-2).
ET infants were those born from 37+0 to 38+6 weeks. For this study, we defined term infants as those born from 39+0 to 41+6weeks. Gestational age was assessed by early first trimester ultrasound and, when unavailable, by last menstrual age.
The instruments used for this study were the Baseline In-Hospital Interview, the One-Month Follow-Up Interview questionnaires, and the Dennis' Breastfeeding Self-Efficacy Scale–Short Form (BSES-SF).
The Baseline In-Hospital Interview questionnaire was adapted for the present study by the primary investigators (A.N. and L.N.) from the Centers for Disease Control and Prevention Infant Feeding Practices Study II.19 Mothers were interviewed by a research assistant within the first 72 hours after birth during the postpartum hospitalization. The initial interview took between 15 and 20 minutes. The One-Month Follow-Up Interview questionnaire used selected questions from the Infant Feeding Practices Study II.19 The research assistant contacted the mother by phone and conducted a phone interview, which took 10 minutes. All data for the study, including breastfeeding rates, were obtained from the maternal oral interviews.
Dennis' BSES-SF consists of 14 statements that measure breastfeeding self-efficacy (BSE) using a five-point Likert scale ranging from 1 to 5 (not at all confident—very confident), with scores ranging from 14 to 70.20 The higher the score, the higher the level of BSE. Dennis reported a Cronbach's alpha of 0.94. For the present study, the BSE was measured at both the postpartum hospitalization and 1-month interviews, and Cronbach's alpha at both times was 0.91.
Breastfeeding rates for this study included several variables: breastfeeding in the first hour of life, age of infant at breastfeeding initiation, any breastfeeding, exclusive breastfeeding, and breastfeeding intensity during the postpartum hospitalization and at 1 month. Breastfeeding in the first hour was defined as infant's receiving any breast milk in the first hour of life. Breastfeeding rates at 1 month of age were calculated with a feeding history for the 7 days before the phone interview. Any breastfeeding was defined as receiving any breast milk either at the breast or pumped milk. Exclusive breastfeeding for this study was defined as receiving only mother's milk via the breast or pumped milk. Exclusive breastfeeding at 1 month was defined as exclusive breastfeeding for the 7 days before the 1-month interview. Breastfeeding intensity was defined as the percentage of all feedings that were breast milk. High breastfeeding intensity was defined as a breastfeeding intensity >80%.
Data were analyzed using SPSS 24. Descriptive statistics were used to summarize the data and identify characteristics of the mothers and newborns in the two groups, and t-tests, Pearson correlation, chi-square, Fisher exact, and Mann–Whitney Utests were performed for interval, nominal, and ordinal variables, respectively. The relationship between background and clinical variables was analyzed using Pearson correlations. Logistic analysis was used to calculate the unadjusted and adjusted odds ratios (aORs) for breastfeeding outcomes in the ET and term groups. Maternal immigrant status, marital status, obese/overweight, work intention in the first year, study intention in the first year, gravida, was breastfed, breastfed in the past, delivery type, and epidural were included as confounding variables in the adjusted analysis. The study received approval from the Internal Review Board at the Hadassah Medical Organization, and the study participants signed an informed consent form.
The study sample composed of 370 infants; 12 mothers declined to consent for the study. Of the 358 remaining infants, 200 were classified as ET infants and 158 were term infants. The mean maternal age was 31 years, and 98% of all mothers were married. The mothers' highest educational degree was: 19% of mothers graduated high school, 4% post-high school certificate, 40% had a Bachelor's degree, 21% had a Master's degree, and 4% had a Doctoral degree. Eighty-two percent of the mothers intended to work in the first year and 27% intended to return to school. There were no significant differences between the groups for education (Mann–Whitney U = 14,992, p = 0.780) or income levels (U = 14,638, p = 0.26). The background variables for the two groups are given in Table 1. Of note, less ET mothers intended to return to school in the first year and less delivered vaginally. As expected, birth weight was lower among ET infants (3,082  g versus 3,313  g, p < 0.001). There were no differences between the groups in maternal health problems, including diabetes and pre-eclampsia
|Characteristic||ETa(n = 200)||Terma(n = 158)||p|
|Maternal age, years|
|<25||16 (8)||20 (13)||0.207|
|25–34||125 (63)||101 (64)|
|>34||59 (29)||37 (23)|
|Married||196 (98)||156 (99)||0.211|
|Immigrant||68 (34)||60 (38)||0.284|
|Work intention <1 year||160 (80)||133 (84)||0.640|
|Study intention <1 year||42 (21)||55 (35)||0.004|
|Maternal health problem||20 (10)||24 (15)||0.188|
|Maternal overweight/obese||54 (27)||32 (20)||0.170|
|Mother was breastfed||152 (76)||133 (84)||0.147|
|Primiparous||46 (23)||35 (22)||0.899|
|Breastfed prior child||146 (73)||115 (73)||0.846|
|Vaginal delivery||140 (70)||145 (92)||0.000|
|Vaginal induction||4 (2)||6 (4)||0.144|
|Vaginal epidural||92 (46)||79 (50)||0.450|