*4.1. Animals*

Adult female Sprague Dawley rats were given with a single intraperitoneal injection of streptozotocin (STZ) (65 mg/kg) to induce diabetes. At 3 days after STZ injection, plasma glucose concentrations were measured using a glucose analysis kit. The diabetic state was defined as a plasma glucose concentration exceeding 19.5 mmol/L (180 mg/dL). Both normal and diabetic females were mated overnight with normal male rats. Pregnancy was confirmed by the presence of sperm in vaginal smears. The same day that sperm appeared in vaginal smears was designated day 0 of gestation. All animals were housed under controlled temperature (23 ◦C) and a 12 h light/dark cycle, and they had free access to standard rat chow and tap water. The protocols for all animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of Harbin Medical University (approval code: QC2017089; approval date: 1 October 2017).
