Why do some women not know they're pregnant?

Good question: Many times it is an intense psychological state of denial. The symptoms are there, but the mind refuses for some reason to acknowledge the pregnancy, perhaps form some psychological trauma or fear. Severe obesity obviously can hide the physical aspects of pregnancy, but the breast engorgement and lack of menstruation will still be present.

Good question: Some women dont know they re pregnant because pregnancy symptoms are alike other symptoms when you are not pregnant. Also sometimes is hard to see a belly in someone that is already overweight. Also sometimes a lack of knowledge in terms of body symptoms can lead to this as well.

Being Pregnant: Not usually until after a period is missed. True early pregnancy is symptom free.

Irregular period: the first sign is usually missing period if someone have usually irregular period they may not know they are pregnant and some people have very little symptoms they dont realize till late