Pandanus amaryllifolius and Tectona grandis Extracts Improve Fetal Outcomes in Streptozotocin-Induced Gestational Diabetes in Rats

Gestational diabetes mellitus (GDM) causes adverse effects on both mothers and offspring. This study investigated the effects of a polyherbal formulation combining Pandanus amaryllifolius root and Tectona grandis leaf extracts on maternal and fetal outcomes in streptozotocin (STZ)-induced GDM rats, compared with metformin. Pregnant rats were assigned to a non-diabetic reference group and diabetic groups, including an untreated diabetic group (negative control), a metformin-treated group (positive control), and diabetic groups treated with low, medium, or high doses of the pandan–teak formulation from gestation day 7 to 21. Medium and high doses significantly increased maternal body weight and pancreatic mass index (p < 0.05) without altering maternal glycemia or insulin levels. Fetal weight increased at medium and high doses, whereas crown–rump length increased only at the high dose. Placental index and fetal glucose levels decreased in a dose-dependent manner (p < 0.05), with no significant change in implantation loss. These findings suggest that the pandan–teak formulation may exert complementary actions that support placental–fetal glucose regulation and fetal growth while maintaining maternal glycemic stability, indicating its potential as a plant-based adjunct approach for gestational diabetes focused on fetal protection.