Table 4.

Crude and adjusted relations between periodontitis and preterm birth according to the main causes of preterm birth among women who did not take antibiotics during pregnancy

		Localised Periodontitis*			Generalised Periodontitis†			p value‡
	Number of women (% of cases)	Number (%) of women§	Crude OR|| (95% CI)	aOR¶ (95% CI)	Number (%) of women§	Crude OR|| (95% CI)	aOR¶ (95% CI)
Controls	721	74 (10.3%)	1.0	1.0	79 (11.0%)	1.0	1.0
All preterm births	573	73 (12.7%)	1.36 (0.96–1.92)	1.34 (0.93–1.95)	88 (15.4%)	1.54 (1.10–2.13)	1.45 (1.02–2.07)	0.06
PB for Preeclampsia**	137 (24.2%)	22 (16.1%)	2.06 (1.21–3.50)	2.10 (1.16–3.77)	33 (24.1%)	2.89 (1.81–4.62)	3.19 (1.88–5.43)	0.001
PB for IUGR††	67 (11.8%)	3 (4.5%)	0.47 (0.14–1.55)	0.39 (0.11–1.35)	15 (22.4%)	2.20 (1.18–4.11)	1.73 (0.88–3.41)	0.06
Spontaneous PB or PPROM‡‡	247 (43.7%)	34 (13.8%)	1.39 (0.90–2.15)	1.38 (0.86–2.21)	25 (10.1%)	0.96 (0.59–1.54)	0.93 (0.56–1.56)	0.42
PB for other causes§§	115 (20.3%)	13 (11.3%)	1.15 (0.61–2.16)	1.28 (0.65–2.52)	15 (13.0%)	1.24 (0.68–2.25)	1.00 (0.51–1.98)	0.61

Causes of preterm birth were known for 566 cases

^*PD (probing depth)≥4 mm and CAL (clinical attachment level)≥3 mm on the same site on 2 or 3 teeth

^†PD≥4 mm and CAL≥3 mm on the same site on 4 or more teeth

^‡p-value of the trend test (Wald Khi-2 test)

^§Number (%) of women with respectively localised or generalised periodontitis

^||Crude OR (and 95% confidence interval); all preterm birth (PB) compared to controls; each of the 4 groups of cases compared with the group of controls

^¶OR (and 95% confidence interval) adjusted for maternal age, parity, nationality, educational level, marital status, employment during pregnancy, body-mass index before pregnancy, smoking status, and examiner; all PB compared to controls; each of the 4 groups of cases compared with the group of controls

^**Induced PB for preeclampsia

^††Induced PB for intrauterine growth retardation

^‡‡Spontaneous PB or preterm premature rupture of membranes

^§§Induced PB for other causes