Table 1
Characteristics of 98 mothers with SPTB and 135 controls.
| Parameters | SPTB | Controls | p Value |
|---|---|---|---|
| Mean maternal age (years) | 30.20 ± 4.59 | 30.10 ± 3.92 | 0.28 |
| Smoking during pregnancy % (n) | 8.3 (8) | 2.9 (4) | 0.15 |
| Previous SPTB % (n) | 12.4 (12) | 4.3 (6) | 0.08 |
| In vitro fertilization % (n) | 4.1 (4) | 1.4 (2) | 0.31 |
| Urogenital infections % (n) | 7.2 (7) | 4.3 (6) | 0.35 |
| High blood pressure % (n) | 7.2 (7) | 4.3 (6) | 0.35 |
| Stressful events during pregnancy % (n) | 3.1 (3) | 4.3 (6) | 0.50 |
[i] SPTB: spontaneous preterm birth.
Figure 1
Flowchart of study selection process in the meta analysis.
Table 2
Genotype and allelic distribution of the ADRB2 rs1042713 polymorphism of the 98 SPTB patients and 135 controls.
| Parameters | Genotype Frequencies n (%) | Allele Frequencies (n) % | |||||||
|---|---|---|---|---|---|---|---|---|---|
| AA | GA | GG | p Value | χ2 | A | G | p Value | χ2 | |
| SPTB cases | 17 (17.3) | 48 (49.0) | 33 (33.7) | 0.99 | 0.01 | 65 (42.0) | 81 (42.0) | 1.0 | 0 |
| Controls | 24 (18.0) | 66 (49.0) | 45 (33.0) | 90 (58.0) | 111 (58.0) | ||||
[i] SPTB: spontaneous preterm birth.
Table 3
Association of ADRB2 rs1042713 with SPTB under different genetic models.
| Genetic Model | WSPTBvs.WC | |||
|---|---|---|---|---|
| OR (95% CI) | p Value | χ2 | ||
| Dominant | GA+GG vs. AA | 1.03 (0.52-2.04) | 0.92 | 0.01 |
| Recessive | AA+GA vs. GG | 0.98 (0.57-1.70) | 0.92 | 0.01 |
| Codominant | AA+GG vs. GA | 0.99 (0.59-1.68) | 0.92 | 0.01 |
[i] SPTB: spontaneous preterm birth; OR: odds ratio; 95% CI: confidence interval; WSPTB: SPTB women; WC: control women.
Table 4
Characteristics of studies included in the meta analysis.
| Refs. | Year | Country | Population | PPROM Excluded | SPTB Cases Criteria | Case Sample Size | Control Criteria | Control Group Size |
|---|---|---|---|---|---|---|---|---|
| this study | 2017 | Slovenia | Caucasian | no | GA <37 | 98 | GA >37 | 135 |
| [30] | 2013 | Korea | Asian | no | GA <37 | 166 | GA >37 | 289 |
| [31] | 2004 | Hungary | Caucasian | no | GA <37 | 32 | GA >37 | 127 |
| [33] | 2002 | Turkey | Caucasian | yes | GA <37 | 80 | GA >37 | 76 |
| [32] | 2002 | USA | Hispanic | no | GA <37 | 28 | GA >37 | 251 |
[i] PPROM: preterm premature rupture of the membranes; SPTB: spontaneous preterm birth; GA: gestational age.
Figure 2
Forest plots for the association between the ADRB2 rs1042713 polymorphism and SPTB risk in recessive and dominant genetic models.
Figure 3
Effects of the ADRB2 rs1042713 A allele on the ADRB2 receptor.