Skandapurana 5.165.26

5.165.26

tataḥ puṃsa vane snāte te śubhe cārulocane ..
dadhāte garbhamevātha bhartuḥ saṃyogataḥ kṣaṇāt .. 26 ..

Then, having bathed after the rite of puṃsavana, those two auspicious, fair-eyed women / instantly conceived a pregnancy through union with their husbands. // 26