trophoblast human 86 controlled study 70 priority journal 70 human cell 68 Female 66 Humans 64 Trophoblasts 64 female 62 Pregnancy 60 article 56 metabolism 50 leptin 48 pregnancy 48 Placenta 46 protein expression 46 Leptin 38 placenta 38 signal transduction 36 cell line 34 Western blotting 32 in vitro study 32 Article 30 Cell Line 28 nidation 26 vasoactive intestinal polypeptide 26 apoptosis 24 protein phosphorylation 24 Vasoactive Intestinal Peptide 22 cytology 22