Randomized clinical trial of the effect of the onset time of skin-to-skin contact at birth, immediate compared to early, on the duration of breastfeeding in full term newborns

A randomized multicentre parallel clinical trial was conducted in two second-level reference hospitals in the Sabana Centro Cundinamarca region (Hospital El Salvador de Ubaté and Hospital Universitario de La Samaritana – Unidad Funcional de Zipaquirá) between November 2018 and January 2020.

The study protocol was approved by the ethics committee of Universidad de La Sabana (N° 70–2018) and Hospital Universitario de La Samaritana (N° 0302–18). The parents of the neonates signed an informed consent for inclusion in the study prior to the start of and/or in the latent phase of labour and before randomization. There was a data monitoring and security committee headquartered at the Contract Research Organization (CRO). The researchers were planned an interim analysis from the protocol when completing 50% of the sample size (150 newborns) followed up to 3 months.

Full term newborns with appropriate weight for gestational age, born from single gestation and by vaginal birth, with spontaneous neonatal adaptation, stable at birth, with indication for maternity and whose mother expressed desire to breastfeed were included. Neonates with congenital malformations, mothers with perinatal complications, patients with indication for separation of the mother-child pair at the time of birth and mother-child dyads with known contraindications for breastfeeding were excluded.

The primary outcome was the percentage of neonates with exclusive breastfeeding at 6 months. Secondary outcomes were the percentage of infants with exclusive breastfeeding at 3 months, duration in months of exclusive breastfeeding, neonate’s breastfeeding ability evaluated by the Infant Breastfeeding Assessment Tool (IBFAT) in the first 24 h and/or before discharge and categorized into effective vigorous breastfeeding (IBFAT score ≥ 10) and non-effective breastfeeding (moderately effective and weak sucking and/or no feeding; IBFAT score < 10) [21, 22], percentage of weight change between birth and the first week of life (less than or equal to 7% and greater than 7%), and hospitalization in the neonatal unit in the first week.

For the primary outcome, a survey was applied at the follow-ups with the neonates developed according to WHO recommendations for breastfeeding practices [23]. The type of foods and supplements given to the infant during the past month was asked, categorizing the feeding practice into [24]: exclusive breastfeeding, predominant breastfeeding, partial breastfeeding and complementary feeding. Last, based on this information, the results were categorized into exclusive breastfeeding and non-exclusive breastfeeding. Exclusive breastfeeding was considered the time in months with human milk as the only source of food with no other liquids or solid foods given [23].

For the application of the IBFAT, prior to the start of recruitment an educational strategy and a pilot test were performed to standardize the use of the instrument. The weight change in the first week was evaluated in the face-to-face follow-up in the first week of life, and it was measured on the same electronic scale used at birth. The need for hospitalization was investigated at this same follow-up; when the mother reported hospitalization, the event was reviewed and documented with the medical record.

The mother-child dyads were randomly allocated to one of two study groups, immediate SSC and early SSC, through a computer-generated process centralized in the CRO and with a strategy of permuted blocks with size of six. The allocation numbers were kept hidden in opaque and sealed envelopes; they were only consecutively revealed in the final expulsion phase of labour by the study monitor assigned to the centre. Due to the characteristics of the study intervention, blinding was only applied to the group of researchers who analysed the data.

SSC between mother and child was defined as placing the naked newborn in the prone position, wearing a diaper and cap, on the mother’s naked thorax (between the breasts), with both covered by a warm blanket [1]; the duration of SSC in both groups was established as 1 h (60 min).

Immediate SSC was defined as the intervention initiated in the first minute after birth, with performance of the immediate neonatal adaptation manoeuvres (thermoregulation, umbilical cord clamping and immediate neonate assessments) during SSC but postponing subsequent manoeuvres (neonate evaluations and screenings) until the end of the SSC duration. Early SSC was defined as the intervention that began exactly at 60 min of life of the newborn. In this group, thermoregulation and umbilical cord clamping were performed according to the protocol of the health institution, after which the neonate was placed under a radiant warmer to complete the neonatal adaptation interventions; once these were completed, the neonate was dressed and placed next to the mother, initiating the SSC at 60 min of life. In both study groups, during the SSC, the neonate was monitored with a pulse oximeter, three-lead EKG, axillary temperature measurement and continuous medical surveillance, recording these data at the beginning and end of the intervention. Mothers were advised and supported to initiate early breastfeeding (first hour of life) in both groups.

The neonates were followed-up for a total period of 6 months. The first follow-up was performed at discharge from the maternity ward, when the IBFAT score was evaluated. The second follow-up was performed in the first week of life (between five to 7 days of life) in person in the doctor’s office. The weight and need for hospitalization during the first week of life were recorded. Subsequently, monthly follow-ups were conducted by telephone by applying the survey to evaluate the practice of breastfeeding.

The sample size was calculated considering a baseline risk of exclusive breastfeeding at 6 months for Colombia of 24% [25], and considering that we found no studies evaluating the two onset times of SSC, the data in Moore et al. were used [26], who reported that SSC compared to separation at birth increases exclusive breastfeeding between three and 6 months of age (relative risk [RR] 1.97, 95% CI 1.37, 2.83), for a power of 80% and a Type I error probability of 5% with expected losses to follow-up of 30%. Thus, a total sample size of 300 neonates was estimated (150 in each group).

Descriptive data analyses were performed using measures of central tendency, position and dispersion for the continuous variables and absolute and relative frequencies for the categorical variables. The assumption of normality was evaluated with the Shapiro-Wilk test. The association between the time of onset of SSC and categorical variables (exclusive breastfeeding at six and 3 months, percentage of weight change, hospitalization in the first week of life and newborn’s breastfeeding behaviours) were evaluated by constructing contingency tables and evaluating the independence between variables with the Chi² test and/or Fisher’s exact test according to the assumption of number of cases per cell. The RR was calculated as a measure of effect along with its 95% confidence interval (95% CI).

A survival analysis was performed to evaluate whether the time of onset of SSC has an effect on the duration of exclusive breastfeeding. For the analysis, the final event was the absence of exclusive breastfeeding. The event time was defined from the time of onset of the intervention until the month that exclusive breastfeeding was documented. In participants who were lost to follow-up, this time was censored until the last follow-up in which exclusive breastfeeding was documented. Survival functions were constructed using the non-parametric Kaplan-Meier method for the total cohort and by SSC onset time group. Survival functions were compared using the log-rank test. A Cox proportional hazards analysis was performed to estimate the hazard ratio (HR) with the 95% CI of exclusive breastfeeding suspension. Subgroup analyses were also performed for variables considered to possibly interact with the evaluated interventions (early breastfeeding, newborn breastfeeding behaviours, hospitalization in the first week of life and receiving breastfeeding education at discharge from the maternity ward). The proportionality assumption was confirmed by Cox regression models.

For data collection, input and management, the electronic data capture tool REDCap (Research Electronic Data Capture) housed at the Institute for the Evaluation of Health Care Quality (Instituto para la Evaluación de la Calidad y Atención en Salud - IECAS) was used. Data analysis was performed in STATA version 14. Because an interim analysis was planned from the protocol, the p - value was adjusted for multiple analyses, defining a value of p < 0.025 as the level of significance.