Brood of Bones is a fantasy story by A.E. Marling, who has made it available as a free digital audiobook. It is Book 1 in a series titled The Enchantress and is narrated by Henrietta Meire. The audiobook is also available for purchase through Audible (see link below).
Cursed with endless drowsiness, Enchantress Hiresha sleeps more than she lives. Since she never has had a chance to raise a family, she sometimes feels like every woman is pregnant except for her.
This time, she is right. From virgin to grandmother, all the women in her city have conceived. One unexpected pregnancy is a drama; fifty thousand is citywide hysteria.
A lurking sorcerer drains power from the unnatural pregnancies, and Hiresha must track him by his magic. Unfortunately, her cultured education in enchantment ill equips her to understand his spellcraft, which is decidedly less than proper. The only person uncivilized enough to help is the Lord of the Feast, a dangerous yet charming illusionist. Associating with him may imperil Hiresha's city, yet refusing his help will allow the sorcerer to leech godlike power from the mass births.