Table 1 Demographic characteristics and univariate logistic regression models for prediction of ongoing pregnancy at day 45 post-LH surge.

Characteristic	Pregnant (n = 36)	Non-pregnant (n = 107)	Odds ratio	CI	P	C statistic
Age (years)	35.0 (4.5)	34.7 (4.7)	1.02	0.94,1.10	0.69	0.51
Current smoker n (%)	4 (11%)	23 (22%)	0.46	0.15,1.44	0.18	0.55
SIMD quintile
1 Most affluent, 5 most deprived)
1	6 (17%)	21 (20%)	0.57	0.17,1.92	0.78	0.57
2	8 (22%)	21 (20%)	0.80	0.25,2.52
3	8 (22%)	32 (30%)	0.50	0.16,1.52
4	5 (14%)	15 (14%)	0.67	0.18,2.42
5	9 (25%)	18 (17%)	referent
Systolic blood pressure (mmHg)	116 (13)	115 (12)	1.01	0.98,1.04	0.59	0.53
Diastolic blood pressure (mmHg)	65 (7)	66 (9)	0.98	0.94,1.03	0.40	0.54
Height (cm)	165 (7.2)	164 (6.7)	1.02	0.97,1.08	0.42	0.55
Weight (kg)	71.5 (11.3)	68.4 (13.6)	1.02	0.99,1.05	0.23	0.58
BMI (kg/m²)	26.5 (4.1)	25.5 (4.7)	1.05	0.97,1.14	0.26	0.58
Waist (cm)	88.6 (10.6)	85.6 (11.6)	1.03	0.99,1.06	0.16	0.59
Menstrual period length (days)	4.6 (1.5)	4.8 (1.0)	0.87	0.61,1.23	0.44	0.57
Cycle length (days)	28.8 (1.74)	28.8 (2.25)	0.99	0.83,1.19	0.92	0.49
Number of previous pregnancies ≥24 weeks
0	35 (97%)	102 (98%)			1.00*
>0	1 (3%)	2 (2%)			1.00*
Number of previous pregnancies <24 weeks
0	27 (75%)	73 (70%)	0.81	0.34,1.91	0.63	0.52
>0	9 (25%)	31 (30%)	0.81	0.34,1.91	0.63	0.52
Number of embryos transferred
1	6 (17%)	18 (18%)	0.92	0.34,2.54	0.88	0.51
>1	30 (84%)	83 (82%)	0.92	0.34,2.54	0.88	0.51
Treatment
IVF	13 (36%)	53 (52%)	0.52	0.23,1.14	0.10	0.58
ICSI	23 (64%)	48 (48%)	0.52	0.23,1.14	0.10	0.58

^*P-value from Fisher’s Exact test.
Continuous variables are presented as mean (standard deviation) and continuous variables as number (%). Odds ratios are for a 1 unit increase in a variable. BMI = body mass index, CI = confidence interval, IVF = in vitro fertilisation, ICSI = intra-cytoplasmic sperm injection, SIMD = Scottish Index of Multiple Deprivation. Missing data are as follows: n = 1 pregnant (smoking status, systolic blood pressure, diastolic blood pressure, height, weight, cycle length); n = 2 pregnant (weight, BMI); n = 4 pregnant (waist); n = 6 pregnant (menstrual period length); n = 1 non-pregnant (age, smoking status, weight, BMI); n = 2 non-pregnant (waist); n = 3 non-pregnant (cycle length, number of previous pregnancies ≥ 24 weeks; number of previous pregnancies <24 weeks); n = 6 non-pregnant (number of embryos transferred; treatment); n = 8 non-pregnant (systolic blood pressure, diastolic blood pressure); n = 13 non-pregnant (menstrual period length).

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