Jessica Simpson Says She Didn't Know She Could Get Pregnant While Breastfeeding: 'Wait, What?' As she makes her highly anticipated return to the music scene, Jessica Simpson is sharing anecdotes about some of the major changes in her private life that took place during her hiatus.

The pop singer performed a medley as part of the NBC breakfast show’s summer concert series, and she’s such a pro that viewers wouldn’t have known anything was amiss.

While Simpson thought breastfeeding acting as a form of birth control, the mom of three was pleasantly surprised when she got pregnant with baby No. 2 just four months after she and ex-husband Eric Johnson welcomed their first child.