LEP and obesity due to melanocortin 4 receptor deficiency: However, we must take into account that the average pregnancy increased weight gain (12.5 kg) [79] is due to the products of conception (fetus, placenta, and amniotic fluid, approximately 5.0 kg) and changes in the mother (enlarged uterus and breast tissue approx. 1.4 kg, and extracellular extravascular and intravascular fluid approx. 3000 mL) and not necessarily due to the accumulation of fat (approximately 3.5 kg), therefore, it is not possible to undoubtedly connect greater BMI with obesity, leptin, or other mechanisms [80].