In SU young women had essentially the same de facto 'opportunities' as young men, not withstanding certain society stereotypes. Actually it was illegal to be

In SU young women had essentially the same de facto 'opportunities' as young men, not withstanding certain society stereotypes. Actually it was illegal to be a 'housewife' (with some legal exclusions). That means - you have to work. After the birth of child and the period of state-mandated maternity leave (3 years in later period) you have to go back to workforce. So the motivation to study was to escape the grueling realities of kolkhoz or factory and achieve a better standard of living. In fact the expectation was the both parents would be working and the child would be in childcare or kindergarten. Which of course put a lot of pressure on women due to reality of being a housewife and a full-time working woman at the same time. There was also a lot of collective pressure - if you do not have a child by certain age you would be considered a failure, which is hard to attribute to communism per se but to certain backwardness and lack of education. But I still think that big difference in fertility is the change from peasant family with 5-8 children to the urban family of 1-2.