Early weight trends after cardiac surgery in infants from low- and middle-income countries where the majority are undernourished have not been defined. We studied the early post-operative weight trends to identify specific factors associated with early weight loss and poor weight gain after discharge following congenital heart surgery in consecutive infants undergoing cardiac surgery at a referral hospital in Southern India.

This was a prospective observational study. Weights of the babies were recorded at different time points during the hospital stay and at 1-month post-discharge. A comprehensive database of pre-operative, operative, and post-operative variables was created and entered into a multivariate logistic regression analysis model to identify factors associated with excessive early weight loss after cardiac surgery, and poor weight gain following hospital discharge.

The study enrolled 192 infants (mean age 110.7 ± 99.9 days; weight z scores − 2.5 ± 1.5). There was a small but significant (p < 0.001) decline in weight in the hospital following surgery (1.6% decline (interquartile range −5.3 to +1.7)); however, there was substantial growth following discharge (26.7% increase (interquartile range 15.3–41.8)). The variables associated with post-operative weight loss were cumulative nil-per-oral duration and cardiopulmonary bypass time, while weight gain following discharge was only associated with age.

Weight loss is almost universal early after congenital heart surgery and is associated with complex surgery and cumulative nil-per-oral duration. After discharge, weight gain is almost universal and not associated with any of the perioperative variables.