Hi Sundus, in a Visit visa, you can stay for 6 months and then your husband has to go to Gharaffa Immigratioin to renew. For some people, they renew for 1 month and while others have renewed for 2 months (6+2). After that the captain will tell you dont come back, so you have to definetly leave the country and yes, you can come back provided your husband has to repeat the whole process of documentation to call you on visit visa again.
Note: The immigration people will not bother about c-section or normal delivery and every day after the visa expires will be charged as 200 Qr per day.
Also plan for the delivery, because the Hamad Hospital delivery will be very less only for RP holders and if people are under visit visa, it costs more, i dont know the price. Hope this info helps you..