Sudden weight lost at week 38 is it a cause for concern?

I lost my weight till i was even lighter than i first visit my gynae at wk 8 but he assured my hb that it doesnt affect the baby. But i know for myself that its due to the controlling of blood sugar, carbs intake is much lower. Although i am now only at wk 24++. But i tink if ur gynae doesnt say anyting, its prob ok?