Materials and Methods: Thyroid function was studied in 64 pregnant primigravida women. The study group comprised of 32 full term pregnant women scheduled for spontaneous vaginal delivery, while the control group included 32 pregnant women at around 32 weeks of gestation. Serum total T3 (TT3), total T4 (TT4) & thyrotropin (TSH) were estimated by high-sensitive radioimmunoassay. In the study group, blood samples were obtained during various phases of labor; Phase A: onset of labor; Phase B: within 2 hours of delivery of placenta
and membranes and phase C: 24-48 hours after delivery (immediate puerperium).