I'm back to the weight I was before I got pregnant
「妊娠前の体重に戻った」= I returned to my pre-pregnancy weight / I've got back to my pre-pregnancy weight / I'm back to the weight I was before I got pregnant
ボキャブラリー
return/be back = 戻る
pre-pregnancy = 妊娠前
weight = 体重
I got back to the weight I was at before I got pregnant.
I weigh the same now as I did before I got pregnant.
この場合、次のような言い方ができますよ。
ーI got back to the weight I was at before I got pregnant.
「妊娠する前の体重に戻った」
ーI weigh the same now as I did before I got pregnant.
「今の体重と妊娠前の体重が同じです」=「妊娠前の体重に戻った」とも言えます。
ご参考まで!