Prediction of premature labor using AIWA's scoring
Authors: Yoshitake H. , Koyama Y. , Fukuda J. , Uehira K. 
Published: March 2003

Purpose:  Clinical investigation into the correlation between AIWA's score and premature labor.

Patients:  Eight hundred and twenty‐nine (829) mothers delivered single baby at AIWA Maternity Hospital in 2000. The number of primipara (P) was 394, while that of multipara (M) was 435. We eventually analyzed 587 deliveries in 829, because the resting 238 deliveries were not fully followed up before delivery and the resting four were undertaken therapeutic premature termination. These 587 mothers had at least one time of AIWA's scoring in both 14–24 weeks of gestation and 25–32 weeks of gestation.

Methods:  We have been using the AIWA's score to detect and prevent premature labor for 4 years, which consists of findings of transvaginal ultrasonography (cervical length and funneling of internal os of the uterus), and internal examination (looseness of external os of the uterus and consistency of the cervix). The full score is 12, which means extremely high risk of premature labor. On the other hand, the score zero means no risk of premature labor. The patients, whose score over 8, should go into hospital to have cervical cerclage. and if multipara has histories of premature deliveries and/or threatened premature labor, P‐score (1–3) is added to AIWA's score according to the degree of the risk. Five hundred and eighty‐seven (587) deliveries were divided in four groups, including (1) over 1 week hospitalization (2) having cervical cerclage (3) premature deliveries (4) normal range deliveries (including OPD therapy and <1 week hospitalization). The distribution of AIWA's score was analyzed separately between nullipara and multipara in 14–19, 20–24, 25–28, and 29–32 weeks of gestation, respectively. In hospitalized patients, the most previous scores before hospitalization was analyzed. And, indications for prophylactic cervical cerclage before 27 weeks of gestation were: (1) nullipara and #8807; 8 (AIWA's score alone), multipara and #8807; 8 (AIWA's score + P‐score) (2) few uterine contraction with negative fetal fibronectin (3) agreements of patients and her family with informed consents. The patients with all three indications had prophylactic cervical cerclages.

Conclusions:  (1) The rate of prophylactic cervical cerclage was 4.5% (nullipara: 1.6%, multipara: 6.6%) in year 2000. This rate was higher than those of many other hospitals. The rate of premature labor after the prophylactic cervical cerclages was 15%, however, all cases of premature labor occurred after 36 weeks of gestation. Eighty‐eight percent (88%) of the operation was performed in 23–27 weeks, while only 12% was operated before 22 weeks of gestation. Seventy‐three percent of cases, which had prophylactic cervical cerclages, had been excellent course during pregnancy without over 1‐month hospitalization and without re‐hospitalization. (2) In the hospitalized case without cervical cerclage for premature labor, total hospitalized days had positive correlation with AIWA's score (P < 0.05). (3) The rate of premature labor and deliveries were 2.8% in nullipara before 37 weeks and 0.7% before 36 weeks, which declined than those in many other hospitals reported before. and there was no delivery before 33 weeks of gestation. (4) The success rates of prediction of premature labor with AIWA's score and #8807; 8 (P), were 48.6% (PPV) and 92.7% (NPV). Those rates seemed better than those of any other hospital reported in the past. (5) According to these four evidences, we can use AIWA's score, which is reproducible and reliable, in order to predict and prevent premature delivery.