The results of this study exhibit, more than half (52%) of the preterm infants in this cohort were introduced to complementary food before 17 weeks corrected age as recommended by the ÖGKJ [6]. The present study`s findings are consistent with previous international research showing that a significant proportion of premature born infants receive their first solid food earlier than recommended [10]. Actually 23% of the preterm infants who were given solids early in Salzburg received complementary food even before 12 weeks corrected age, putting them at risk for developing obesity, Diabetes Mellitus (DM) and coeliac disease as studies show [8].
Previous research has identified predictors of early weaning in preterm infants including male sex, gestational age, younger maternal age, maternal smoking, lower level of maternal education, higher maternal pre-pregnancy BMI and formula-feeding [10].
Results of this study support the finding that formula-feeding increases the odds for an early introduction of complementary feeding. Also symptomatically for that are mothers with non-insulin dependent gestational diabetes. All these mothers in our study started weaning their infants before the corrected age of 17 weeks. Mothers suffering from gestational diabetes usually tend to come into lactation more slowly and to have less breastmilk than healthy mothers, which often leads to early formula feeding. Just as the number of pregnancies, the number of children living in the same household as well as twins being a predictor may be explained by the mother`s lack of time, possible due to lack of supportive help. Having more children to take care of might leave mothers too stressed to keep up breastfeeding for a prolonged period of time, so they start formula-feeding only a few weeks postpartum which leads them to be prone to earlier solid food introduction. Typically, formula fed infants with higher weight percentile at 17 weeks corrected age are weaned early. Additionally, a lower household income is also associated with earlier weaning. It might be speculated that a lower household income is associated with a lower level of maternal education and “normal” family food is cheaper than buying formula. A direct correlation of a lower level of maternal education is not found. As well younger maternal age, higher maternal pre-pregnancy BMI, male sex and gestational age are also not correlated. This may be due to the small sample size. Information on smoking habits was not obtained.
In adherence to data from term and preterm infants [10] the present study also confirms that exclusive and prolonged breastfeeding is positively correlated with a delayed introduction of complementary feeding. Mothers who tend to exclusively breastfeed over a longer period of time were also less likely to stop breastfeeding abrupt when introducing solids, but kept on partially breastfeeding for as long as possible, enabling their infants to profit from human milk
during their weaning period and further on. In comparison, mothers who decided on combined milk feeding during the infant`s first weeks of life tended to completely stop breastfeeding very soon after starting formula-feeding and those mothers were also found to start feeding solids early.
An additional key aspect of this study was to identify the types of food given to preterm infants mainly during the first few weeks of complementary feeding. Again, this study can only provide data on those aspects from the early weaning group.
There is international consensus that from time complementary foods is started, relatively fast – within 2 to 3 weeks complex food containing high energy density, proteins and minerals like iron and zinc should be introduced [5]. Previous research found international discrepancies on weaning foods, particularly on the first solid foods given. While almost 85% of British preterm infants received baby rice as their first complementary food and 6% received fruit or vegetables [10], in Italy almost half of the preterm infants received mashed fruit as their first solids [13]. Fanaro et al. expressed his concern about Italian preterm infants being weaned with low energy and low nutrient-dense food. Meat as part of early solid feeding was offered to only about 10% of infants in the Italian study [13]. For Austrian infants the ÖGKJ recommends starting complementary feeding with bioavailable iron and zinc sources like meat and grains, otherwise it is not mandatory to follow a specific order of food introduction [6]. Those recommendations seem to be very clear and easy to implement. In the present study third of infants in the early weaning group still received only fruits and vegetables at 17 weeks corrected age, although some of them had been weaned as early as 10 weeks corrected age. Almost 90% of preterm infants received vegetable puree as first solid food, the remaining 10% were started on solids with fruit puree. About 25% received a form of milk-free cereal within their first week of complementary feeding; meat was introduced to about 20% of infants in the first week. When mothers were asked about reasons for choosing vegetables or fruit as first solid food the main proportion reported vegetables being recommended by their midwife as best. There seemed to be awareness amongst mothers on nutritional value of foods to some extent, as most of them chose not to introduce their infants to fruits during their first week of weaning because they didn`t want them to get used to foods with high sugar content to soon. Some mothers admitted to buy commercially available baby-food jars because they felt insecure on what type of food to feed their infants. Furthermore they relied on the labelling of the food being age appropriate. If asked about introducing meat, some mothers reported they felt their infants being too small to be fed anything else besides vegetables and fruits. Some mothers reported they felt their infants did not enjoy eating solids and therefore they did not want to overstrain them by introducing too many different types of food.
When asked about if and where they obtained information on introducing complementary feeding to their infant, about half of mothers reported talking with their family paediatrician about introducing solids, most of them during one of their infant routine check-ups, some called or made an extra appointment. Many mothers felt insecure about how and when to wean their premature born infant, even if they already had older children, which is why they set high value on the family paediatrician’s recommendations.
As already mentioned above, this study identified detailed information on caregiver’s reasons for weaning their preterm infant early. More than one third of mothers reported their infant showed increased interest in food during family meal times and they felt breastmilk respectively formula did not satisfy their infant any longer. It is possible that mothers over interpreted those signs of dissatisfaction as infants at this age naturally start putting their hands and toys into their mouths and showing more and more interest to their environment which represents only a developmental step without necessarily expressing readiness for complementary feeding. Another third of mothers started introducing solids to their preterm infants because it was recommended to them by their family paediatrician. We don`t have a definite explanation but some theories as to why paediatricians would recommend early solid introduction to preterm infant’s caregivers. Premature infants represent only a small group of infants who are roughly uniformly distributed to all family paediatricians in Salzburg and its surrounding areas, hence premature born infants are only a fraction of a family paediatrician’s patient clientele. As there are neither distinct guidelines nor much research on solid food introduction for this specific but yet small group of patients, a good proportion of family paediatricians just might not know about the current recommendations. Also most of infants in this study cohort were late preterm infants with little to no long-term health problems at the age of solid food introduction, which could lead to paediatricians overlooking their prematurity when giving complementary feeding recommendations. Supporting this theory would be our finding that when conducting the interviews, it was noticed that especially mothers of late preterm infants who only spent a few days in the NICU (neonatal intensive care unit) or didn`t need any monitoring at all had often forgotten about their child being born prematurely respectively considered it irrelevant by then.
Nearly 10% of mothers felt pressured by their family and close friends to start introducing solids, which can be explained by unawareness of prematurity as well as absent knowledge and understanding of current recommendations and corrected age. About 6% of mothers reported introducing complementary feeding because their infants were 4 months uncorrected age, which supports the assumption that the term “corrected age” is not something all caregivers fully understand. If the data are considered from birth, preterm infants in the present study were weaned with 19.37 weeks ± 2.31 weeks chronological age. If that was the case, mothers would very well follow the current guidelines on weaning their infants and missing compliance would not be as big a problem as previous studies suggest [10].
To our knowledge, this study is the first to explore complementary feeding practices in Austria and there is no similar national data on preterm infants. The classification “preterm” includes a very heterogeneous group with a wide range of gestational age and birth weight; however, most of the infants will be developmentally challenged to some extent, for example poor sucking reflex, reduced respiratory capacities.
One major strength of this study is its prospective design. Because the questionnaires were conducted at exactly 17 weeks corrected age with a maximal variances of one week before or after, recall bias regarding the time of solid food introduction, types of food or reasons for starting complementary feeding is nearly impossible.
To the best of our knowledge there is no other study obtaining detailed information from caregivers on reasons to start weaning their preterm infants. This information seems to be very important to prevent too early introduction of solids in the future. Finally, although the cohort is rather small, it still gives a good insight on the weaning practices of Austrian preterm-caregivers and is, to our knowledge, the first national study on this.
There are a few limitations to the present study. The preterm cohort studied in Salzburg was self-selected and is not representative of the preterm population in general. The rather small study cohort is due to a very limited time frame for recruiting families and because we only recruited infants from Salzburg. Therefore, only assumptions can be made regarding the weaning practices for the rest of Austria. Mean maternal age in this study was 31.54 y ± 5.43, that is slightly older than the mean maternal age of 30.5y in Austria (data obtained from the 2015 report of Austrian Institute for Family Studies). Regarding the types of complementary food given there is only data from the 52% of preterm infants who received solids before 17 weeks corrected age, which was the time of our questionnaire being obtained, as we interviewed the families only once. Naturally, from the infants who had not yet received any solids at 17 weeks, any information on complementary feeding could not be obtained. Also reasons for introducing complementary feeding as well as sources of information on this topic could only be provided by families who had already started weaning their infants.