I am assuming you are a woman of child bearing years asking this question. The answer is that there is no one answer. It could be once or never. The reason for this could be your ovulation cycle ie. when your eggs are ready, or it could be to do with the fertility of your partner's sperm.
Anyway if you are asking this question I truly believe you need some better advice than here. Talk to a doctor or to an older female friend who has perhaps already had children. There is a lot to know about bringing a baby into the world. Many changes take place in your body and your whole system goes into a different way of being. Some women seem hardly affected and hold down a job until the nine months are nearly up. Others feel unable to cope with the pace of life as their bodies are telling them to slow down and care for the unborn child
Anyway if you are asking this question I truly believe you need some better advice than here. Talk to a doctor or to an older female friend who has perhaps already had children. There is a lot to know about bringing a baby into the world. Many changes take place in your body and your whole system goes into a different way of being. Some women seem hardly affected and hold down a job until the nine months are nearly up. Others feel unable to cope with the pace of life as their bodies are telling them to slow down and care for the unborn child