The interruption of everything - Terry McMillan

At forty-four, Marilyn Grimes is facing up to the menopause (something is DEFINITELY up with her hormones), bored to tears by her responsible but unsexy husband Leon, and feeling the strain of having raised three children who may be great kids but who leave her feeling anxious all the time. Her mother-in-law, Arthurine, has moved in, as has Arthurine's beloved elderly dog, Snuffy. Meantime the needs of her own extended family (particularly her crack-head foster sister) are escalating like mad. No wonder Marilyn is feeling tired and hormonal. But everything is interrupted when Marilyn finds out she's not menopausal . . . but pregnant.