A high Nugent score but not a positive culture for genital mycoplasmas is a risk factor for spontaneous preterm birth

Figures & data

Table I.  Clinical characteristics of the study population according to the Nugent score

Characteristics	Nugent score		p-value
	≥8 (N = 137)	<8 (N = 840)
Maternal age (years, mean ± SD)	31 ± 3.5	31 ± 3.4	NS
Primiparity	85 (62%)	446 (53%)	NS
Previous preterm birth	10 (7%)	65 (8%)	NS
Twin gestation	5 (4%)	33 (4%)	NS
Gestational age at sampling (weeks, mean ± SD)	16.6 ± 1.1	16.7 ± 1.4	NS
Gestational age at delivery (weeks, mean ± SD)	38.5 ± 3.3	38.9 ± 2.7	NS
Positive vaginal discharge culture for mycoplasmas	75 (55%)	213 (25%)	<0.001

NS, not significant.

Table II.  Clinical characteristics of the study population according to the result of a vaginal fluid culture for mycoplasmas

Characteristics	Vaginal fluid culture for mycoplasmas		p-value
	Negative (N = 689)	Positive (N = 288)
Maternal age (years, mean ± SD)	31 ± 3.3	31 ± 3.7	NS
Primiparity	364 (53%)	167 (58%)	NS
Previous preterm birth	54 (8%)	21 (7%)	NS
Twin gestation	28 (4%)	10 (4%)	NS
Gestational age at sampling (weeks, mean ± SD)	16.7 ± 1.3	16.7 ± 1.4	NS
Gestational age at delivery (weeks, mean ± SD)	38.9 ± 2.8	38.9 ± 2.8	NS
Nugent score			<0.001
0–3	577 (76%)	178 (24%)
4–7	50 (59%)	35 (41%)
8–10	62 (45%)	75 (55%)

NS, not significant.

Table III.  The frequency of preterm birth according to the Nugent score

	Nugent score		Odds ratio and 95% confidence interval
	≥8 (N = 137)	<8 (N = 840)
Preterm birth (n)
<32 weeks	7 (5%)	20 (2%)	2.2 (0.9–5.3)
<34 weeks	9 (7%)	29 (3%)	2.0 (0.9–4.3)
<35 weeks	12 (9%)	35 (4%)	2.2 (1.1–4.4)*
<36 weeks	14 (10%)	47 (6%)	1.9 (1.0–3.6)*
<37 weeks	19 (14%)	64 (8%)	2.0 (1.1–3.4)*
Spontaneous preterm birth (n/N)
<32 weeks	5/135 (4%)	9/829 (1%)	3.5 (1.2–10.6)*
<34 weeks	6/134 (4%)	13/824 (2%)	2.9 (1.1–7.8)*
<35 weeks	9/134 (7%)	17/822 (2%)	3.4 (1.5–7.8)*
<36 weeks	10/133 (8%)	24/817 (3%)	2.7 (1.3–5.8)*
<37 weeks	13/131 (10%)	35/811 (4%)	2.4 (1.3–4.8)*

*p < 0.05.

Table IV.  The frequency of preterm birth according to the Nugent score and the result of vaginal fluid culture for mycoplasmas

	Group 1	Group 2	Group 3	Group 4	Total
	Nugent score ≥ 8 (+) Culture (N = 75)	Nugent score ≥ 8 (−) Culture (N = 62)	Nugent score < 8 (+) Culture (N = 213)	Nugent score < 8 (−) Culture (N = 627)
Preterm birth (n)
<32 weeks	4 (5%)	3 (5%)	5 (2%)	15 (2%)	27 (3%)
<34 weeks	6 (8%)	3 (5%)	8 (4%)	21 (3%)*	38 (4%)
<35 weeks	8 (11%)	4 (6%)	9 (4%)*	26 (4%)*	47 (5%)
<36 weeks	8 (11%)	6 (10%)	11 (5%)	36 (6%)	61 (6%)
<37 weeks	10 (13%)	9 (15%)	18 (8%)	46 (7%)^b	83 (9%)
Spontaneous preterm birth (n/N)
<32 weeks	3/74 (4%)	2/61 (3%)	2/210 (1%)	7/619 (1%)	14/964 (1%)
<34 weeks	4/73 (5%)	2/61 (3%)	5/210 (2%)	8/614 (1%)*	19/958 (2%)
<35 weeks	6/73 (8%)	3/61 (5%)	6/210 (3%)*	11/612 (2%)*	26/956 (3%)
<36 weeks	6/73 (8%)	4/60 (7%)	6/208 (3%)	18/609 (3%)*	34/950 (4%)
<37 weeks	7/72 (10%)	6/59 (10%)	10/205 (5%)	25/606 (4%)*,**	48/942 (5%)

*p < 0.05 compare to Group 1.

**p < 0.05 compare to Group 2.