Psychologist Nina Strohminger at the University of Pennsylvania, who was not involved in the study, says she wants the effect to be real but cannot rule out some unknown confounding variable.

If that confounding variable can be taken care of, though, and the effect persists, the next obvious step is to determine what mechanism within the mother's body causes the discrepancy.

Pay attention to results subgroup analysis in assessment of efficacy, seek and determine the effect point of intervention measures, make full use of data information and eliminate confounding factors.