Late preterm birth and growth trajectories during childhood: a linked retrospective cohort study
Authors: Yoshida-Montezuma Yulika , Kirkwood David , Sivapathasundaram Branavan , Keown-Stoneman Charles D. G. , de Souza Russell J. , To Teresa , Borkhoff Cornelia M. , Birken Catherine S. , Maguire Jonathon L. , Brown Hilary K. , Anderson Laura N. ,   on behalf of the TARGet Kids! Collaboration, Allen Christopher , D’Annunzio Danielle , Jaleel Mateenah , McFarlane Natricha Levy , Omand Jessica A. , Thadani Sharon , Aglipay Mary , Bayoumi Imaan , M. Borkhoff Cornelia , Carsley Sarah , Charach Alice , Cost Katherine , D’Hollander Curtis , Fuller Anne , Kinlin Laura , Kucab Michaela , Li Patricia , Parkin Pat , Persaud Nav , Rae Sarah , Socynska Izabela , Vanderhout Shelley , Vanderloo Leigh , Wong Peter , Mudiyanselage Piyumi Konara , Li Xuedi , Liu Jenny , Mitchell Michelle , Zaffar Nusrat , Bondoc Tiffany , Buckley Trudy-Ann , Flores Pamela Ruth , Kurt Kardelen , Loganathan Sangeetha , Mali Tarandeep , Thompson Laurie , Batten Jennifer , Chan Jennifer , Clark John , Craig Amy , De Castris-Garcia Kim , Dharman Sharon , Kelleher Sarah , Nasser Salimah , Pabon Tammara , Rhodes Michelle , Salsa Rafael , Skelding Julie , Stern Daniel , Stewart Kerry , Tavares Erika Sendra , Weir Shannon , Zaccaria-Cho Maria , Janus Magdalena , Duku Eric , Reid-Westoby Caroline , Raso Patricia , Offord Amanda , Abraham Emy , Ali Sara , Anderson Kelly , Arbess Gordon , Baker Jillian , Barozzino Tony , Bergeron Sylvie , Bloch Gary , Bonifacio Joey , Bowry Ashna , Calpin Caroline , Campbell Douglas , Cheema Sohail , Chisamore Brian , Constantin Evelyn , Danayan Karoon , Das Paul , De Guerra Viveka , Derocher Mary Beth , Do Anh , Doukas Kathleen , Egger Anne , Farber Allison , Freedman Amy , Freeman Sloane , Gazeley Sharon , Grewal Karen , Guiang Charlie , Handford Curtis , Hanson Laura , Harrington Leah , Jacobson Sheila , Jagiello Lukasz , Jansz Gwen , Kadar Paul , Keiswetter Lukas , Kiran Tara , Knowles Holly , Kwok Bruce , Lahiry Piya , Lakhoo Sheila , Lam-Antoniades Margarita , Lau Eddy , Leduc Denis , Leung Fok-Han , Li Alan , Li Patricia , Male Roy , Meret Aleks , Mok Elise , Moodie Rosemary , Nash Katherine , Owen James , Peer Michael , Perlmutar Marty , Persaud Navindra , Pinto Andrew , Porepa Michelle , Qi Vikky , Ramji Noor , Raza Danyaal , Rouleau Katherine , Ruderman Caroline , Saunderson Janet , Schiralli Vanna , Sgro Michael , Hafiz Shuja , Siam Farah , Shepherd Susan , Srikanthan Cinntha , Taylor Carolyn , Treherne Stephen , Turner Suzanne , Uddin Fatima , Heuvel Meta van den , Weisdorf Thea , Wong Peter , Yaremko John , Ying Ethel , Young Elizabeth , Zajdman Michael , Begum Esmot Ara , Juni Peter , Lakhanpal Gurpreet , Lebovic Gerald , Nnorom Ifeayinchukwu , Nunez Marc Denzel , Stitt Audra , Thorpe Kevin , Assan Raya , Bondar Homa , Charames George S. , Djolovic Andrea , Gorscak-Dunn Chelsea , Hassan Mary , Kandel Rita , Rodrigues Michelle 
Published: September 2023

Abstract
Background
Evidence suggests that accelerated postnatal growth in children is detrimental for adult cardiovascular health. It is unclear whether children born late preterm (34–36 weeks) compared to full term (≥ 39 weeks), have different growth trajectories. Our objective was to evaluate the association between gestational age groups and growth trajectories of children born between 2006–2014 and followed to 2021 in Ontario, Canada.

Methods
We conducted a retrospective cohort study of children from singleton births in TARGet Kids! primary care network with repeated measures of weight and height/length from birth to 14 years, who were linked to health administrative databases. Piecewise linear mixed models were used to model weight (kg/month) and height (cm/month) trajectories with knots at 3, 12, and 84 months. Analyses were conducted based on chronological age.

Results
There were 4423 children included with a mean of 11 weight and height measures per child. The mean age at the last visit was 5.9 years (Standard Deviation: 3.1). Generally, the more preterm, the lower the mean value of weight and height until early adolescence. Differences in mean weight and height for very/moderate preterm and late preterm compared to full term were evident until 12 months of age. Weight trajectories were similar between children born late preterm and full term with small differences from 84–168 months (mean difference (MD) -0.04 kg/month, 95% CI -0.06, -0.03). Children born late preterm had faster height gain from 0–3 months (MD 0.70 cm/month, 95% CI 0.42, 0.97) and 3–12 months (MD 0.17 cm/month, 95% CI 0.11, 0.22).

Conclusions
Compared to full term, children born late preterm had lower average weight and height from birth to 14 years, had a slightly slower rate of weight gain after 84 months and a faster rate of height gain from 0–12 months. Follow-up is needed to determine if growth differences are associated with long-term disease risk.