Motor development in toddlers prenatally exposed to maternal cancer treatment: a national cohort study in the Netherlands

BACKGROUND: Limited knowledge exists on the impact of prenatal exposure to maternal cancer (treatment) on child motor development. We aimed to assess motor outcomes in toddlers and explore potential associations with perinatal and treatment-related factors.

METHODS: This national cohort study reports a cross-sectional analysis of children prenatally exposed to maternal cancer who completed the planned 18-month motor assessment at the national Cancer in Pregnancy offspring outpatient clinic (2018-2024), Princess Máxima Center for Pediatric Oncology. Motor development was assessed using the Bayley Scales of Infant and Toddler Development (BSID-III-NL), with outcomes expressed as Z-scores compared with Dutch norms (delay defined as Z < -1). Multivariable linear regression examined associations between predefined prenatal exposures (gestational age at birth, birthweight, timing of maternal treatment, chemotherapy, systemic therapy) and postnatal family burden with motor outcomes. This study is registered with ClinicalTrials.gov, NCT00330447.

FINDINGS: Of 102 eligible children, 96 (94.2%) were included (mean age 19.8 months; mean gestational age 36.8 weeks). Mean Z-scores were -0.38 (95% CI: -0.56, -0.20) for gross motor and 0.09 (95% CI: -0.08, 0.25) for fine motor development. Delayed gross motor development was observed in 32 children (33%), and delayed fine motor development in 16 children (17%). Regression analyses showed no significant associations between gross motor development and the studied prenatal or postnatal factors. Fine motor scores were lower in children with lower gestational age at birth (β = 0.085; 95% CI: 0.011, 0.159) and higher postnatal family burden (β = -0.736; 95% CI: -1.211, -0.261).

INTERPRETATION: At 19 months, one in three children exposed to maternal cancer during pregnancy demonstrated delayed gross motor development. Mean gross motor scores were significantly lower compared with the BSID-III-NL normative population, whereas fine motor development did not differ from reference values. Neither gross nor fine motor development was associated with prenatal exposure to chemotherapy or systemic therapy. Fine motor outcomes were associated with gestational age and postnatal family burden. These findings highlight the need for structured motor surveillance in this population.

FUNDING: KWF Kankerbestrijding (KWF) grant number 13192.