Part of the reason Natasha, now 34, wasn’t getting pregnant was that her eggs weren’t of very high quality, which happens more frequently with age. But researchers figured out that they could remove the mitochondria from stem cells that develop into eggs, found in her own ovarian tissue. Then the stem cell mitochondria could replace the mitochondria in the old egg which, when fertilized, behaves like a younger egg and makes IVF treatments more successful. (Previous cases of mitochondrial replacement, which have not yet resulted in children, used mitochondria from a third person, but in this case the new mitochondria were from Natasha, as was the egg.) When Natasha and Omar did traditional IVF, they got only one viable embryo; using the new technique, they had four. One of those eggs became Zain, and the another two were frozen in case the Rajanis want to have another child.