Or HaChaim on Exodus 1:12/אור החיים על שמות א׳:י״ב

1 וכאשר יענו אותו כן ירבה, The more they oppressed them the more they increased. There is a beautiful explanation by the Zohar second volume page 95 on Kohelet 8,9. Solomon says that "there is a time when one man rules over another to his detriment." The Zohar explains that when one has to endure persecution and troubles, the good [which may have been mixed with the evil. Ed.] is distilled from the evil joining other areas which are totally good; by the same token the evil of that mixture joins other areas of pure evil. These two details are hinted at when Solomon speaks of לרע לו. Similarly, the Torah here tells us the same thing. The more persecution the Israelites suffered the more "good" was released from what had been only a mixture of good and evil previously. With the release of that "good", i.e. good qualities, the Israelite families merited having more and more children. Hence the Torah adds the words וכן יפרץ in the sense of ופרצת ימה וקדמה, "You will burst forth to the West and to the East, etc." Alternatively, the word may mean "it achieved a breaking forth" i.e. a separation from an environment in which the good had been forced to mix with the evil. The evil was now released and separated. This resulted in the famous "iron crucible" in which the character of the Israelite people was forged in Egypt.

2The plain meaning of the verse is that for every unjustified act of cruelty by the Egyptians, G'd compensated the Jewish people with a commensurate increase in the number of babies that were born to them. Additional hands enabled the parents to meet the work quota imposed upon them by the Egyptians. The words כן ירבה, "so they would multiply," would then mean that the additional number of children made up for the reduced performance by their weakened parents in proportion to the emasculating effect of the hard labour. This became a vicious circle as the Egyptians kept increasing the workload.