When a lady bears children, her rewards are multiplied manifold. It is said that two rakaats of prayer of a pregnant woman is 80 times superior to that of a normal woman.
The Prophet (sallallahu alaihi wa sallam) is reported to have said: "O Muslim women! Does it not please you that during your pregnancy, for every day that passes, you get the reward of fasting while out in the path of Allah; and that for every night that passes, you get the reward of spending the whole night in worship. Then when the pains of labour start, and you bear them patiently, no one on this earth or in the Heavens knows of the comfort that Allah has prepared for you. When the child is born, you get the reward of performing 70 years of Nafl (voluntary) prayer and keeping Nafl fasts. Then when you breastfeed the child, for every gulp of milk you will be rewarded, and for every night you stay awake to see to your baby you get the reward of freeing 70 slaves in the path of Allah and one year of Nafl worship. When you complete breastfeeding your child, the Angels come and pat you on the back, saying: "Congratulations! All your minor sins are forgiven…"
If a woman dies during childbirth, then she dies as a martyr (one who gives his life fighting in the path of Allah).
Tribute to Muslim Mothers
[Quoted from Al Muzakkir]