Table 4

Curve estimations by cubic equations for the percentage of CS

Independent variables	R²	F statistic	p Values	Constant	b1	b2	b3
TRUST titre	0.95	23.04	0.006	−2.65	1.42	−0.02	0.00^*
Gestational month at treatment	0.98	78.16	<0.001	−3.13	4.83	−1.41	0.12
Gestational week×log (1/T)^†	0.99	64.32	0.003	−5.61	1.20	−0.05	0.00^*

Log (1/T), the log of the reciprocal the TRUST titre in the mother; R², coefficient of determination of the model; b1 is the coefficient estimate for independent variable x, b2 for x², and b3 for x³.
↵* The value is less than 0.001.
↵† The interaction between gestational week at treatment for maternal syphilis and log (1/T).
TRUST, toluidine red unheated serum test.