Nipple stimulation and its timing during the breastfeeding process have a strong impact on the HPA axis, which causes a significant decrease in cortisol [18] and an increase in prolactin in plasma [20]. Our study showed the influence of early breastfeeding with skin-to-skin contact on maternal and umbilical cord serum cortisol levels which decreased if breastfeeding occurred early after childbirth (p = 0.0272).

The assessment of suckling function in a newborn during the first days of life and correction of abnormalities are extremely important for successful breastfeeding in later months. However, in order to breastfeed, which is a natural source of food, the neonate should exhibit certain skills, have properly developed oral cavity structures, and express appropriate oral reflexes [19]. Moreover, the effect of nipple shields used to protect the nipples on breastfeeding duration is unclear. Although nipple shields appear to have no impact on the plasma prolactin and cortisol levels among lactating mothers, they may reduce milk removal from the mammary gland [20,21,22]. In this study, the newborns’ suckling skills were assessed to determine the relationship between suckling skills and the duration of breastfeeding as well as the measured prolactin and cortisol levels. All the assessed newborns had a properly built hard palate (a parameter related to the structure of the oral cavity). The most frequently observed oral reflex abnormality (10 children, 18%) was an exaggerated biting reflex; however, it had no influence on further breastfeeding in the studied group. The basic reflexes of seeking and suckling were found to be important to maintain breastfeeding at three months of life, as well as the parameters related to breast grasping and suckling, namely champing and smacking, the depth of grasping the nipple and the correct embracing of nipple by the lips, the wide opening of the mouth before grasping the nipple, and the open angle between the lips after grasping the nipple. For efficient milk intake, the correct rhythm of suckling, series of suctions, and position of the tongue (an element of the oral cavity) were found to be crucial. For continuing breastfeeding at six months of life, the key parameter was the wide opening of the mouth after the baby’s medial cleft touches the nipple.

All subjects began breastfeeding in the hospital. After three months of childbirth, 52% of mothers were still exclusively breastfeeding, with the number of feedings per day varying between 5 and 15. After six months, 44% continued to breastfeed, with 1–12 feedings (on the child’s demand); all mothers had already introduced complementary feeding at this time and were not exclusively breastfeeding. The European Society for Paediatric, Gastroenterology, Hepatology and Nutrition (ESPGHAN) [23, 24] recommends baby-led weaning, which refers to introducing the baby to the taste of food, from the 17th week of life. However, this consists in an infant’s gradual learning of the taste of new products by licking and sucking, which does not replace breastfeeding and is therefore not qualified as full complementary feeding [24].

According to the report published by the Centre for Disease Control and Prevention (CDC) in 2020, in the United States 84.1% of mothers initiated exclusive breastfeeding in the hospital, and after three months, 46.9% were exclusively breastfeeding and at six months 25.6% continued exclusive breastfeeding [25]. These data and the results of the present study seem to be of concern because exclusive breastfeeding of infants up to six months of age is still the recommended mode of nutrition for the general population [23]. Complementary feeding is recommended only when an infant needs to be supplemented with foods rich in particular nutrients (e.g. iron) [25]. However, the expert panel of the Polish Society For Paediatrics Gastroenterology, Hepatology and Nutrition emphasizes that even partial or shorter breastfeeding can provide sufficient benefits to a child [23].

In this study, during telephone interviews at 3 and 6 months after birth, the reasons stated by mothers who had started regular feeding with modified milk or weaned the child from breastfeeding were milk shortage, lack of weight gain in the child, and frequent waking up and anxiety of the child (respondents believed that infants fed with modified milk were calmer). When asked about the help they received in terms of lactation counseling, most of the mothers indicated difficulties or, for various reasons, inability to obtain reliable advice, as well as a lack of knowledge about breastfeeding among midwives and pediatricians. The first two reasons indicate the need for structured lactation counseling after the discharge of mother and child from the hospital, with a focus on assessing the infant’s suckling function, observing the act of feeding, and evaluating the third stage of lactogenesis in mothers. These data are in line with a report published by the Centre for Lactation Science in 2018 [23], which highlighted that nearly 54% of Polish mothers who were discharged from the hospital felt that they would need additional assistance with breastfeeding. Moreover, the CDC experts [25] emphasize that mothers should be provided with individualized support in the first hours and days after birth to enable them to achieve their lactation goals.

The breastfeeding rates in Europe have been shown to be very low. Theurich et al. assessed breastfeeding rates in 11 European countries (Belgium, Croatia, Denmark, Germany, Ireland, Italy, The Netherlands, Norway, Spain, Sweden, and Switzerland) [26] and found that at the age of six months 35–65% of infants were breastfed and 13–39% were fully/exclusively breastfed in those countries. The relatively high rate of exclusive breastfeeding after 3 and 6 months postpartum (69% and 67%, respectively) observed in the present study may be related to the mothers’ decision to exclusively breastfeed their children for a long period and the breastfeeding consultation provided to them on the second day postpartum, of the two blinded midwives who assessed the neonatal suckling skills, one was an IBCLC and the other was a CLE.

In the context of the above recommendations and significant difference in breastfeeding rates between Europe and the United States, it seems reasonable to profoundly investigate the key reasons for difficulties in maintaining exclusive breastfeeding and develop ways to overcome them. Our study assessed term, healthy, naturally born babies, and even in our study group 14 (23%) mothers did not start breastfeeding during the first two hours postpartum. Moreover, 10 newborn babies assessed in our study (18%) were fed formula on the second day postpartum, which is consistent with the CDC report [25] showing that in 2017, infant formula was given to 19.2% of newborns even before the second day of life. Thus, a fundamental question arises regarding the prospect of the breastfeeding support offered in maternity wards and the multifactorial impact on the success of breastfeeding among new mothers [27, 28].