Niki Taylor

Niki Taylor is expanding her brood: the model is pregnant with another baby.

"Wooohooo!! YES!! We r expecting our 4th child!! So happy & blessed!!" she tweeted along with a picture of her sonogram Thursday.

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Taylor, 36, and her husband, NASCAR driver Burney Lamar, married in December 2006 and have a 2-year-old daughter named Ciel. Taylor is also mom to identical 16-year-old twin sons Hunter and Jake from her previous marriage.