Adam Clarke Bible Commentary

Therefore God dealt well with the midwives: and the people multiplied, and waxed very mighty - This shows an especial providence and blessing of God; for though in all cases where females are kept to hard labor they have comparatively easy and safe travail, yet in a state of slavery the increase is generally very small, as the children die for want of proper nursing, the women, through their labor, being obliged to neglect their offspring; so that in the slave countries the stock is obliged to be recruited by foreign imports: yet in the case above it was not so; there was not one barren among their tribes, and even their women, though constantly obliged to perform their daily tasks, were neither rendered unfruitful by it, nor taken off by premature death through the violence and continuance of their labor, when even in the delicate situation mentioned above.