In this large population-based and representative sample of newly delivered mothers from three US states, we found that prenatal intention to breastfeed is strongly and directly predictive of breastfeeding initiation and continuation. Women who reported definite intention to breastfeed were highly likely to succeed in doing so, as 98.4% initiated breastfeeding, while women with tentative intention were less successful, as only 69.8% initiated, and those who were uncertain were less successful still, as only 39.7% initiated. Compared with women who expressed tentative intention, women expressing definite intention to breastfeed were 26.6 times more likely to initiate breastfeeding, 7.1 times more likely to breastfeed for at least four weeks, and 2.8 times more likely to breastfeed for at least ten weeks. Older maternal age, higher maternal education, and higher socioeconomic status (as indicated by insurance type) were also significant predictors of breastfeeding initiation and duration.
We found an important adjusted relationship of infant gestational age with breastfeeding outcomes. Mothers of preterm infants less than or equal to 34 weeks were more than two times more likely
to initiate and continue breastfeeding for at least four weeks than were mothers of term infants. However, these mothers were only 55% as likely as mothers of term infants to continue breastfeeding for at least ten weeks. Given that the hospital stay for infants in this gestational age range is typically 6–20 weeks, this finding suggests that educational efforts in the NICU to encourage breastmilk expression and feeding were successful, but that support for continued breastfeeding at home was lacking. Mothers of late preterm infants (34–36 weeks) were significantly less likely to breastfeed for ten weeks as were mothers of term infants. Our results echo those of Donath and Amir, who found that Australian women delivering at 35–36 weeks gestation were less likely than those delivering at term to initiate breastfeeding (88.2% vs. 92–93.9%), and that by six months of age, mothers of these late preterm infants were over twice as likely to have ceased breastfeeding as those delivering at term 28
. The Australian results and ours suggest that late preterm infants, who represent two-thirds of the preterm infants born in the US 11
, were a group at high risk for breastfeeding failure.
Other authors have looked at the impact of prematurity on breastfeeding decisions in small convenience samples using primarily qualitative methods. Sweet studied a group of 44 mothers of VLBW infants in Australia in 2008, reporting that breastfeeding intention was developed early in pregnancy, and that preterm birth did not change this intention22
. Lucas and Cole reported that intention to breastfeed was more common in mothers of preterm infants (mean BW 1370 g) who were older, married, and delivered male infants, but that infant gestational age played no role 21
. Kaufman and Hall and Jaeger and colleagues reported that breastfeeding intention (or lack therof) is established at the time of delivery of a preterm or sick infant, but that some women do change their mind and breastfeed when they initially planned to feed formula 19, 20
. Social support from family, peers, and medical providers can influence these decisions, and can influence breastfeeding duration 20
. However, none of these studies looked at breastfeeding duration as a function of prematurity systematically and specifically, with a comparison to term infants, as we have done in our study.
Because of these findings, we conducted a stratified analysis of breastfeeding intention on all three breastfeeding outcomes adjusting for gestational age alone, and demonstrated that levels of intention did not differ by gestational age category, reinforcing the importance of infant gestational age in breastfeeding success. Based on our findings, mothers of preterm infants in all gestational age categories represent a group at risk for poor long-term breastfeeding outcomes.
Our study of a large representative sample of women from three US states reinforces findings found in recent smaller studies in other countries. In a cross-sectional sample of 450 pregnant Irish women who delivered term infants, positive intention to breastfeed was associated with an OR of 244 for breastfeeding initiation, compared with no intention 8
. A study of 341 Dutch mothers who delivered term infants also found prenatal intention to be associated with an OR of 405.8 for breastfeeding intention. The investigators described the factors involved in formation of a positive intention to breastfeed, including positive personal attitudes toward breastfeeding, negative personal attitudes toward formula feeding, positive social norms for breastfeeding at home and work, social support for breastfeeding at home and work, and high self efficacy for breastfeeding. In fact, when these factors were included in models to predict breastfeeding initiation, no demographic variable remained a significant predictor, suggesting that breastfeeding behavior depends mostly on factors related to social support and womens’ own self-efficacy and attitudes 9
Several other large-scale studies have also found a strong relationship between breastfeeding intention and behavior. DiGirolamo and colleagues 29
used the 1993–94 Infant Feeding Practices Survey to assess the impact of prenatal breastfeeding intention and breastfeeding behavior in a sample of 1665 primarily White, well-educated US women, recruited in the third trimester of pregnancy. The investigators assessed breastfeeding behavior for 12 months after delivery, comparing the prenatal predicted of duration of breastfeeding to the actual duration. They demonstrated that prenatal intention to breastfeed impacts breastfeeding behavior. Women with no intention of breastfeeding were 405 times less likely to initiate breastfeeding than those who intended to breastfeed for 12 months, and women who planned to stop before two months were 48 times more likely to have breastfed for fewer than ten weeks than were those who intended to breastfeed for at least 12 months 29
. Donath and Amir 10
analyzed a large population-based sample of 10548 women from the Avon Longitudinal Study of Pregnancy and Childhood, a prospective cohort study of women and children from the UK. At 32 weeks’ gestation, women were asked to predict their duration of breastfeeding, and breastfeeding outcomes were monitored for 12 months after delivery. They found that anticipated breastfeeding duration was strongly predictive of breastfeeding behavior. Women who intended to breastfeed longer, suggestive of greater commitment to breastfeeding, had higher rates of breastfeeding initiation: 96.6% of women who intended to breastfeed for at least four months initiated breastfeeding, while only 74.7% of those who intended to breastfeed for less than four weeks initiated 10
Although the PRAMS instrument does not allow us to match intended duration of breastfeeding to actual breastfeeding duration, if the responses to the PRAMS breastfeeding intention question are considered in an ordinal fashion, with a spectrum of definite intention, tentative intention, uncertain intention, and no intention, our analysis also demonstrates that level of intention is important in predicting behavior. Tentative and uncertain intention were associated with greater likelihood of breastfeeding initiation than no intention, but not of continuation at either four or ten weeks, suggesting that a stronger degree of commitment resulted in longer term breastfeeding success, similar to the results reported in the US by DiGirolamo et al 29
and in the UK by Donath and Amir 10
The major strength of our study lies in the robust sampling methods employed by PRAMS, which allowed us to evaluate the impact of breastfeeding intention on breastfeeding outcomes in a population representative of all live births in three US states over three years. In contrast to other studies of breastfeeding intention and subsequent breastfeeding behavior, our sample was larger than all, and was one of only two studies utilizing a population-based sample. Our results are generalizable to much of the US population. Importantly, the PRAMS data allowed us to determine the impact of prematurity on breastfeeding outcomes, adjusting for breastfeeding intention, while previous studies have excluded premature infants, particularly those born before 34 weeks, by design.
Our study is subject to some limitations. PRAMS subjects are sampled only once, typically when the index infant is between 6 weeks and 6 months of age. As 95% of respondents in our sample returned the survey when their infants were 10 weeks or older, we were able to examine breastfeeding continuation to only 10 weeks. Additionally, breastfeeding intention information was collected postnatally, and remote from the delivery of the infant. This may have created recall bias, as women may have tended to report their actual behavior as their “intention”. We were also unable to determine the effect of predicted breastfeeding duration on actual duration, as these questions are not part of the PRAMS instrument.
The determinants of breastfeeding behavior are clearly multiple, and include factors both intrinsic and extrinsic to mothers themselves. Our study adds to the body of knowledge regarding breastfeeding intention and subsequent breastfeeding behavior. Our study provides a novel report of the impact of breastfeeding intention on breastfeeding outcomes in mothers delivering prematurely. We have demonstrated that intention to breastfeed, as reported postnatally, is an extremely powerful predictor of breastfeeding initiation, with an impact almost 12-fold greater than the next most significant factor, prematurity, and that intention strongly affects continuation to at least four weeks and at least ten weeks. Large population-based prospective studies of prenatally-reported intention to breastfeed are needed to verify the strength of this predictor of breastfeeding outcomes. Further research is needed into the factors influencing maternal intention to breastfeed, with the aim to develop interventions to promote development of positive intention to breastfeed prior to pregnancy or delivery.