Background Although the length of gestation has been shown to have an effect on pregnancy outcomes including birth weight, information regarding its effect on postnatal growth of children is scanty. The aim of this study was to assess the potential factors affecting duration of gestation, and how it associates with postnatal growth outcomes of children under two years.

Methods This was an analytical health facility-based, cross-sectional study. A systematic random sampling technique was used, to select mother–child pairs who sought services from child welfare clinic (CWC) in the Tamale Teaching Hospital. The predictors of gestational age were identified using multivariable linear regression and hierarchical multivariable linear regression analysis was used to test the independent contribution of gestational age to length-for-age z-score (LAZ).

Results The prevalence of late term/post-term delivery was 75 (23.5%). Older women were positively associated with longer gestational age as a unit increase in age of the mother increased gestational age by 0.28 standard units, β = 0.28, (95% CI: 0.07 to 0.20). Malarial infection during pregnancy reduced duration of gestation by 0.11 standard units, β = -0.11, (95% CI: -0.79 to -0.02). Greater weekly gestational rate of weight gain reduced gestational age by 0.12 standard units, β = - 0.12, (95% CI: -0.005 to -0.01)

An increase in one week of gestational age was associated with 0.16 increase in LAZ [beta coefficient (β), = 0.16 (95% CI: 0.09 to 0.36)]. However, wasting was 2 times more common among the children born late/post term, AOR= 2.18 (95% CI: 1.25, 3.82, and p = 0.006), compared to children born at term (37-40 weeks).

Conclusions After rigorous adjustment for confounding factors, post-term pregnancy was associated with a higher risk of thinness but protected against stunting in preschool-age children. These findings suggest that post-term pregnancies may have complex and potentially conflicting effects on the long-term growth and development of children.

The authors have declared no competing interest.

N/A

N/A

The author(s) received no specific funding for this work.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Not Applicable

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ethical clearance was obtained from Kwame Nkrumah University of Science and Technology (CHRPE/AP/240/22).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Not Applicable

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Not Applicable

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Not Applicable

All relevant data are within the manuscript and its Supporting Information files.

N/A