Our Gemara on Amud Beis discusses the halakhic principle that one should not marry a woman who is still nursing a child, as she may become pregnant, and this could disrupt her milk supply.  The Gemara wonders why this concern is only active with the second husband, as even with her first husband she might become pregnant and interrupt the milk supply?  The Gemara concludes that in either case, the woman will use birth control.  However, should she become pregnant when married to the biological father of the nursing child, she won’t be bashful of the financial burden and they will make provisions to concoct baby formula or find a wet nurse. However, if the nursing child is a step child of her current husband, she may not pursue the nutritional needs of her current child out of fear of her new husband’s resentment, leading to endangerment of the child.

The idea that what should not get pregnant because it will endanger the needs of a current child is used in a novel manner by Rav Henkin (Benei Bonim 30) to allow for birth control.  The idea being, if there is a credible belief that the mother will not have the emotional resources to care for her current children if she becomes pregnant, then using the same rationale of this Gemara, birth control is indicated.  Rav Henkin considered this a rationale that can be used for longer than two years, as it was also customary to nurse longer than two years, and this often would suspend menses and fertility. We never found the rabbis suggestinf that women should wean after a certain length of time in order to fulfill the Mitzvah of having children. Ergo, the care needs of the current child takes precedence to the Mitzvah of having more children. According to Rav Henkin, a stay at home mom, would be halakhically justified to practice birth control for several years, so long as she genuinely believed she needed to space her children by a number of years in order to give each child the nurture he or she needs. Some authorities have reported a custom in Lithuania that women should use birth control as a standard two years after childbirth, justified by this concern of the welfare of the current child. It also is notable, that Rav Moshe Feinstein (Iggeros Moshe EH I:64) strenuously objected to the existence and historical validity of this reported custom.

I will conclude that though Rav Moshe objected to the halakhic validity of this argument on a sweeping basis, it is arguable that he might have agreed with application of this idea in a individual circumstance. The basic ethic of this Gemara is irrefutable, namely that having more children cannot be at the expense of the health of a current child or children. Therefore, in an individual circumstance, the mother’s emotional resources and ability to be available for her current child might be used as part of a halakhic argument for birth control.  In fact, I have had experience with Rabbanim who indeed utilized this line of reasoning in their psakim.