Which of the following drug regarding transfer of drug across placenta is false

Heparin and insulin are anticoagulant and anti diabetic drug of choice respectively,in pregnancy .Because these have minimum entry into placenta Fetal plasma is more acidic than mother ,so ion trapping of basic drugs occur. (pH7 as compared to pH 7.4 of mother ) Placenta contain p-glycoproteins that can act as reflux pump for drugs. Placental transfer of drug is more in late pregnancy than early pregnancy because uterine cirulation increases and trophoblastic layer becomes thinner as pregnancy advances. Refer G&G 11/e p9-10