Not a chance. There are two reasons why:

1. Nynaeve Delved Aviendha at the beginning of TPOD, after Elayne almost blew them up with unraveling her Gateway from the Kin farm [TPOD: 20, Into Andor, 390]. From [WH: 11, Ideas of Importance, 274], we see that Delving is a very thorough examination. If Aviendha had been pregnant, she would have been about four months along at that point, and there's no way Nynaeve wouldn't have detected it - that's a big physiological change, even if the woman isn't showing it externally. And it's absurd to think Nynaeve would detect such a life-changing condition and decide not to tell Aviendha about it. Therefore, if Avi was pregnant, she'd know.

    

2. And that's why the sister-bonding ceremony in WH's prologue is proof that Avi is not pregnant. Monaelle explains that Melaine is not present at the ceremony because "the babes she carries would be part of the bond between you and Aviendha, if the weaves brushed them. If they survived, that is; the unborn are not strong enough for this" [WH: Prologue, Snow, 48]. Aviendha would not have participated in the ceremony if she were pregnant.

We do know, however, that Aviendha will be pregnant in the future (see section 4.2).