Table 5.

Stability of Hormone Concentrations at Each Timepoint Across Subsequent Pregnancies

Hormone	Gestation Timepoint (wk)	N	F-statistic	DF	Adjusted R2	P
ACTH	25	20	3.5	1,18	0.115	.079a
	31	20	5.9	1,18	0.206	.026b
	37	19	6.4	1,17	0.231	.022b
pCRH	25	19	0.0	1,17	−0.058	.921
	31	19	1.3	1,17	0.015	.273
	37	19	6.4	1,17	0.232	.0213b
Cortisol	25	17	5.8	1,15	0.230	.030b
	31	18	9.9	1,16	0.342	.006c
	37	18	1.6	1,16	0.032	.228
Estradiol	25	19	4.5	1,17	0.164	.048b
	31	18	6.8	1,16	0.253	.019b
	37	18	0.0	1,16	−0.061	.877
Progesterone	25	19	22.6	1,17	0.546	.000d
	31	20	5.0	1,18	0.176	.038b
	37	18	12.4	1,16	0.401	.003c

Abbreviations: DF, degrees of freedom; ns, not significant.

Regression analyses measure the proportion of variance in PREG 2 hormone levels attributable to variance in PREG 1 hormone levels at each of three timepoints (25, 31, 37 weeks' gestation).

Cortisol data were residualized by time of day at collection. For null results, negative adjusted R² values are interpretable as zero.

P < .10 are in bold. See Supplemental Tables 2 and 3 for model details.

^aP < .10.

^bP < .05.

^cP < .01.

^dP < .001.