God allows all to take birth & give birth to further generations to carry his own world in future. GOD does not make any male / female incompetent to produce a child. However sometimes there are some bad spots / Dosh which may be in your Kundli / Kundli of your earlier generations. These factors sometimes restrict your ability to give birth to a child but it has remedy. A proper astro analysis of your Kundli makes you aware.