Fig. 4

Relationship between obstetric factors impacting P1/P2 and chondrogenic differentiation. a Proportion of proteoglycans, stained by Alcian Blue, was measured using a custom-written Image J program. Bivariate regression analysis showed an increase in proteoglycan synthesis by differentiated cells in the presence of managed labor. b Sox-9 expression relative to RP29 was assessed by RT-PCR. Multivariate regression analysis showed a significantly reduced expression of Sox-9 at day 28 of differentiation in cells from smoking mothers. *p ≤ 0.05 after bivariate regression analysis; **p ≤ 0.05 after multivariate regression analysis