Breastfeeding of preterm infants. Associated factors in infants, mothers, and clinical practice.

Abstract

Breastfeeding has even more pronounced health benefits for preterm infants than for full-term infants, but preterm infants are less breastfed. There is no consensus in Danish neonatal intensive care units (NICUs) about which clinical methods facilitate breastfeeding. Skin-to-skin contact between infant and parent is the first step in the breastfeeding process for preterm infants, but studies of toleration

of skin-to-skin contact in extremely preterm infants – less than 28 gestational weeks – are sparse.

The overall aim of this thesis was to study and identify factors associated with breastfeeding of preterm infants, in infants, mothers and clinical practice in order to gain more knowledge of how to guide mothers of preterm infants in breastfeeding. This thesis is based on three studies: Study A, a clinical intervention study with 22 clinically stable extremely preterm infants that investigated infants’ tolerance of skin-to-skin contact with their parents; Study B, a national survey of breastfeeding support at all Danish NICUs; and Study C, a national prospective cohort study of breastfeeding preterm infants with the participation of 1,221 mothers and their 1,488 preterm infants at a gestational age of 24-36 weeks. Regression analyses were used to investigate factors associated with early establishment of exclusive breastfeeding, exclusive breastfeeding at discharge and adequate duration in accordance with the Danish Health and Medicines Authority’s recommendations.

The results showed that the extremely preterm infants in Study A, with mean weight 702 grams, tolerated skin-to-skin contact with their parents with no significant differences in mean skin temperature, heart rate, respiration rate, or oxygen saturation before, during, and after skin-to-skin contact. In Study B, the NICUs reported that they aimed for early skin-to-skin contact, and in 81% of the infants, skin-to-skin contact was initiated within the first 24 hours of life, but significantly fewer of the extremely preterm infants did so. In Study B, the NICUs described support of breastfeeding as being highly prioritised, reflected in skin-to-skin contact and parents’ presence at the NICU, recommendations of breast milk expression, supplementation feedings via feeding tubes, and avoidance of the use of infant feeding bottles as a common practice.

Of the 1,488 preterm infants in Study C, 99% initiated breastfeeding, at discharge, 68% were exclusively breastfed, 17% were partially breastfed, and 31% were exclusively breastfed for an adequate duration following discharge.

Factors in infants, mothers and clinical practice were associated with exclusive breastfeeding. Extremely preterm infants and multiples established exclusive breastfeeding at a higher postmenstrual age (PMA) and had twice the odds of not being exclusively breastfed at discharge. Mothers with low and intermediate education, with less breastfeeding experience, or who smoked had higher odds of inadequate duration of exclusive breastfeeding.

Admitting mothers to the NICU together with the infant immediately after delivery was associated with 1.5 (95% CI 0.3-2.6) days earlier establishment of exclusive breastfeeding. Initiation of breast milk expression showed a dose-response effect: the later the initiation, the higher the odds ratio (OR) for failure of exclusive breastfeeding at discharge and inadequate duration of exclusive breastfeeding.

Nipple shield use was associated with failure of exclusive breastfeeding at discharge (OR 2.3 (95% CI 1.6-3.2)) and inadequate duration of exclusive breastfeeding (OR 1.4 (95% CI 1.1-1.9)). Minimising the use of a pacifier during breastfeeding establishment was associated with 1.2 (95% CI 0.1-2.3) days earlier establishment of exclusive breastfeeding and showed a protective effect for exclusive breastfeeding at discharge (OR 0.4 (95% CI 0.3-0.6)). Test weighing the infant also showed a protective effect for exclusive breastfeeding at discharge (OR 0.6 (95% CI 0.4-0.8)).

Breastfeeding milestones were generally reached at different PMAs for various GA groups, but preterm infants were able to initiate breastfeeding early, with some delay in infants less than GA 32 weeks.

The results indicate that it is possible to establish early skin-to-skin contact with clinically stable extremely preterm infants. Danish preterm infants initiate breastfeeding to the same extent as full-term infants. Breastfeeding competence is not developed at a fixed postmenstrual age, but is influenced by multiple factors in infants, mothers and clinical practice. Admitting mothers to the NICU immediately after delivery seems to contribute to earlier establishment of exclusive breastfeeding. Minimising the use of pacifiers during breastfeeding establishment, restricting the use of nipple shields, encouraging early initiation of breast milk expression, and test weighing of infants may facilitate exclusive breastfeeding in preterm infants.

More support and attention should be given to groups with a higher risk for failure of exclusive breastfeeding: preterm infants with a gestational age of less than 32 weeks, multiples, mothers who smoke, have lower education or less breastfeeding experience.

Abstract (Swedish)

Abstract in Danish

Amning har sundhedsmæssige fordele for mor og barn og mere udtalte fordele for præmature børn, men udenlandske undersøgelser viser, at færre præmature børn påbegynder amning, og færre præmature børn ammes i 4 og 6 måneder sammenlignet med mature børn. Der findes ikke danske undersøgelser om andelen af præmature børn, som påbegynder amning, men en dansk undersøgelse viser, at 60 % af de præmature børn ammes fuldt ved udskrivelse til hjemmet. Der er ikke enighed mellem danske neonatalafdelinger eller international forskningslitteratur om, hvilken klinisk praksis der fremmer amning. Hud-mod-hud-kontakt mellem det præmature barn og forældrene er det første skridt i ammeetablering hos præmature børn, men undersøgelser af hud-mod-hud-kontakt med ekstremt præmature børn under 28 gestationsuger er sparsomme.

Afhandlingens overordnede formål var at identificere og undersøge faktorer der har sammenhæng med amning af præmature børn - både faktorer hos børn, mødre og i den kliniske praksis - for at danne mere viden og kunne vejlede mødre til præmature børn om amning på et evidensbaseret grundlag.

Afhandlingen består af tre undersøgelser. Studie A: et interventionsstudie om ekstremt præmature børn tolererer hud-mod-hud-kontakt med deres forældre med deltagelse af 22 stabile børn født før 28 gestationsuger, Studie B: en national spørgeskemaundersøgelse af ammeforhold på alle 19 danske neonatalafdelinger, og Studie C: en national spørgeskemaundersøgelse af amning af præmature børn med deltagelse af 1.221 mødre og deres 1.488 præmature børn med gestationsalder (GA) 24-36 uger. Vi undersøgte hvilke faktorer, der havde sammenhæng med tidlig etablering af fuld amning, fuld amning ved udskrivelse til hjemmet, og varigheden af fuld amning i henhold til Sundhedsstyrelsens anbefalinger.

De ekstremt præmature børn i Studie A havde på undersøgelsestidspunktet en gennemsnitlig postmenstruel alder (PMA) på 26 uger og 5 dage og en gennemsnitlig vægt på 702 gram. Børnene tolererede hud-mod-hud-kontakten med forældrene uden betydende forskelle i gennemsnitlig hudtemperatur, puls, respiration eller ilt-saturation før, under og efter hud-mod-hud-kontakten, hvilket betyder, at det er muligt at etablere tidlig hud-mod-hud-kontakt med stabile ekstremt præmature børn.

Neonatalafdelingerne beskrev, at de stræber efter tidlig etablering af hud-mod-hud-kontakt, og 81 % af de præmature børn påbegyndte dette indenfor det første levedøgn, men væsentlig færre af de ekstremt præmature børn. Neonatalafdelingerne beskrev at forholdene for amning generelt var gode afspejlet i hud-mod-hud-kontakt, forældres tilstedeværelse, anbefalinger for udmalkning, tilskud med sonde, og tilbageholdenhed med brug af sutteflasker.

Af de deltagende børn påbegyndte 99 % amning, ved udskrivelse var 68 % fuldt ammede og 17 % var delvist ammede, 31 % af børnene levede op til Sundhedsstyrelsens anbefaling om varigheden af fuld amning.

Faktorer hos børn, mødre og i klinisk praksis havde sammenhæng med amning af præmature børn. Ekstremt præmature børn samt tvillinger og trillinger, etablerede fuld amning senere (ved en højere PMA), og havde dobbelt så høj risiko for ikke at være ammet ved udskrivelse. Mødre med kort og mellemlang uddannelse, med kortere ammeerfaring, og mødre der røg havde større risiko for utilstrækkelig længde af fuld amning. Førstegangsfødende etablerede fuld amning halvanden dag senere end flergangsfødende.

Klinisk praksis havde også betydning. At medindlægge moderen på neonatalafdelingen direkte efter fødslen viste større mulighed for at etablere fuld amning nogle dage tidligere, 29 % af mødrene blev medindlagt direkte. Børn der anvendte suttebrik havde dobbelt så stor risiko for ikke at være ammet fuldt ved udskrivelse og halvanden gang så stor risiko for utilstrækkelig længde af fuld amning, men anvendelsen af suttebrik havde ikke indflydelse på, hvor tidligt børnene etablerede fuld amning. Børn, hvor brugen af narresut blev minimeret under ammeetableringen, etablerede amning en dag hurtigere, og havde dobbelt så stor chance for at være fuldt ammede ved udskrivelsen. Brug af kontrolvejning, dvs. at veje barnet lige før og efter en amning, viste halvanden gang større chance for at være fuldt ammet ved udskrivelsen, men havde ingen sammenhæng med hvor tidligt eller hvor længe barnet blev fuldt ammet. Der var stor forskel mellem neonatalafdelingerne på, hvor mange børn der havde anvendt suttebrik, narresut og kontrolvejning under indlæggelsen.

Hvor tidligt moderen påbegyndte udmalkning af modermælk viste en dosis-responseffekt på fuld amning ved udskrivelse og anbefalet varighed af fuld amning, jo tidligere, jo mere positivt for amning, men ikke alle resultater havde statistisk styrke. Mødre, der påbegyndte udmalkning senere end 48 timer efter fødslen, havde fem gange forhøjet risiko for ikke at amme fuldt ved udskrivelse, og mødre der påbegyndte udmalkning mellem 12 og 24 timer efter fødslen havde halvanden gang større risiko for utilstrækkelig længde af fuld amning. Dosis-responseffekten tillader dog at anbefale, at udmalkning påbegyndes tidligt efter fødslen.

Vi kan konkludere, at stabile ekstremt præmature børn tolererer hud-mod-hud-kontakt med deres forældre. Danske præmature børn påbegynder amning i samme grad som mature børn.

Præmature børns ammekompetencer bliver ikke udviklet ved en fast alder, men har sammenhæng med forhold hos børn, mødre og i klinisk praksis. At medindlægge mødrene på neonatalafdelingen direkte efter fødslen, kan formentlig medvirke til tidligere etablering af fuld amning. Det ser ud til, at minimering af brug af narresut under ammeetableringen, begrænsning i brug af suttebrikker, påbegyndelse af udmalkning tidligst muligt efter fødslen og anvendelse af kontrolvejning fremmer amning af præmature børn. Der savnes dog forskning i, hvordan mødre støttes, når kontrolvejning stoppes ved barnets udskrivelse, da disse mødre hurtigere holder op med at amme fuldt.

Ekstra støtte og opmærksomhed bør gives til grupper med større risiko for ikke at amme fuldt, dvs. de ekstremt og meget præmature børn, tvillinger/trillinger, mødre der ryger, har kortere uddannelse eller kortere ammeerfaring.



Popular Abstract in English

The overall aim of the thesis was to study and identify factors associated with breastfeeding of preterm infants in the infant, the mother and clinical practice. This thesis is based on three studies: a clinical intervention study with 22 clinically stable extremely preterm infants investigating infant tolerance of skin-to-skin contact with their parents; a national survey of breastfeeding support at all Danish NICUs; and a national prospective cohort study of breastfeeding preterm infants with participation of 1,221 mothers and their 1,488 preterm infants with a gestational age of 24-36 weeks investigating factors associated with early establishment of exclusive breastfeeding, exclusive breastfeeding at discharge and adequate duration.

The results showed that the extremely preterm infants, with mean postmenstrual age (PMA) 266/7 weeks and mean weight 702 grams at study time, tolerated skin-to-skin contact with no significant differences in mean skin temperature, heart rate, respiration rate, or oxygen saturation before, during, and after skin-to-skin contact. The survey showed that Danish NICUs described the support of breastfeeding as a high priority, as reflected in skin-to-skin contact and parental presence at the NICU, practice of breast milk pumping and supplementation via feeding tubes, and avoidance of the use of infant feeding bottles as a common practice. Of the preterm infants, 99% initiated breastfeeding; at discharge, 68% were exclusively breastfed and 17% partially breastfed, and 31% were exclusively breastfed for an adequate duration. Breastfeeding competences were not developed at a fixed PMA, but were influenced by multiple factors in infants, mothers and clinical practice, as was the case with exclusive breastfeeding. Extremely preterm infants established exclusive breastfeeding at a higher PMA, and had twice the risk of not being exclusively breastfed at discharge. Low education, less breastfeeding experience, and smoking were maternal factors negatively associated with exclusive breastfeeding. Admitting mothers to the NICU together with the infant immediately after delivery was associated with 1.5 (95% CI 0.3 – 2.6) days earlier establishment of exclusive breastfeeding. Initiation of breast milk expression showed a dose-response effect: the later the initiation, the later the establishment of exclusive breastfeeding, and the higher the odds ratio (OR) for failure of exclusive breastfeeding at discharge and inadequate duration. The use of nipple shield was associated with failure of exclusive breastfeeding at discharge (OR 2.3 (95% CI 1.6–3.2)) and inadequate duration of exclusive breastfeeding (OR 1.4 (95% CI 1.1–1.9)). Minimising the use of a pacifier during breastfeeding establishment and test weighing the infant were positively associated with exclusive breastfeeding at discharge (OR 0.4 (95% CI 0.3–0.6) and OR 0.6 (95% CI 0.4–0.8)).

The results of this thesis may contribute to guiding mothers of preterm infants in breastfeeding.

• author: Måstrup, Ragnhild
• supervisor: Inger Hallström; Gorm Greisen; Hanne Kronborg; Bo Mølholm Hansen
• opponent: Associate professor Flacking, Reneé, Dalarna University
• organization: Department of Health Sciences
• publishing date: 2014
• type: Thesis
• publication status: published
• subject: Health Sciences
• in: Lund University Faculty of Medicine Doctoral Dissertation Series
• volume: 2014:58
• pages: 84 pages
• defense location: SSSH-salen, Health Sciences Centre, Institutionen för Hälsovetenskaper, Lund
• defense date: 2014-05-23 13:00:00
• ISSN: 1652-8220
• ISBN: 978-91-87651-84-7
• language: English
• LU publication?: yes
• id: d406da0f-7bdb-4c43-a910-c08af984cee9 (old id 4431661)
• date added to LUP: 2016-04-01 13:12:43
• date last changed: 2019-05-22 06:30:10