Could Aspirin Treatment Modify the Assessment of the Uterine Arteries?

To analyze whether acetylsalicylic (ASA) intake modifies the mean uterine arteries pulsatility index (UtA-PI) at the 2nd or 3rd trimester in a cohort of pregnant women with abnormal mean UtA-PI at between 11 and 14 weeks of gestation.

Methods

This is a retrospective cohort study. Singleton pregnancies with abnormal mean UtA-PI at between 11 and 14 weeks of gestation were studied. The participants were divided into 3 groups: 1) If the participant did not take ASA during pregnancy; 2) If the participant took ASA before 14 weeks of gestation; and 3) If the participant took ASA after 14 weeks of gestation. The mean UtA-PI was evaluated at the 2nd and 3rd trimesters, and it was considered to improve when it decreased below the 95th percentile. The prevalence ratio (PR) and the number needed to treat (NNT) werecalculated.

Results

A total of 72 participants with a mean UtA-PI>95th percentile at the 1st trimester of gestation were evaluated. Out of the 18 participants who took ASA, 8 participants started it before 14 weeks of gestation and 10 after. A total of 33.3% of these participants had improved the mean UtA-PI at the 2nd and 3rd trimesters of gestation, although it was not statistically significant (p=0.154). The prevalence ratio was 0.95 (95% confidence interval [CI]: 0.31-1.89), but between the 1st and 2nd trimesters of gestation, the PR was 0.92 (95%CI: 0.21-0.99) and it was statistically significant.

Conclusion

The present work demonstrates a modification of the mean UtA-PI in participants who took ASA compared with those who did not. It is important to check if ASA can modify the normal limits of uterine arteries because this could have an impact on surveillance.

Keywords:
aspirin; pre-eclampsia; ultrasonography; doppler; uterine artery

Characteristics	No-ASA n = 54	ASA group before 14 weeks n = 8	ASA group after 14 weeks n = 10
Maternal age (years old)	27.9 ± 7.3	31.2 ± 7.1	25.1 ± 5.6
First-trimester GA assessment (weeks)	12.8 ± 0.6	12.7 ± 5.8^ Indicates statistically significant differences between groups aspirin before 14 weeks and after 14 weeks.	12.4 ± 0.6
Second-trimester GA assessment (weeks)	21.7 ± 1.3	20.9 ± 0.8	21.3 ± 1.1
Third-trimester GA assessment (weeks)	29.5 ± 1.0	28.9 ± 0.6	28.9 ± 0.6
Ethnic origin
Mixed	54 (100)	8 (100)	10 (100)
Primigravida	18 (33.3)	0 (0)	4 (40)
Comorbidities
Diabetes mellitus	0 (0)	0 (0)	1 (10)
Chronic hypertension	1 (1.85)^* * Indicates statistically significant differences between aspirin versus no aspirin groups	3 (37.5)	1 (10)
Obesity	4 (7.4)	2 (25)	0 (0)
Chronic renal failure	0 (0)	0 (0)	1 (10)
Anemia	1 (1.85)	1 (12.5)	0 (0)
Hypothyroidism	0 (0)^* * Indicates statistically significant differences between aspirin versus no aspirin groups	0 (0)	4 (40)
Low maternal weight	4 (7.4)	1 (12.5)	1 (10)
Smoker
Yes	9 (16.6)	2 (25)	3 (30)
No	45 (83.3)^* * Indicates statistically significant differences between aspirin versus no aspirin groups	6 (75)	7 (70)
Personal history of PE	2 (3.7)^* * Indicates statistically significant differences between aspirin versus no aspirin groups	3 (37.5)	2 (20)
Family history of PE	7 (12.9)^* * Indicates statistically significant differences between aspirin versus no aspirin groups	3 (37.5)	4 (40)
BMI (kg/m²)	24.9 ± 4.1	27.5 ± 5.8	23.8 ± 3.2

Characteristics	Prevalence ratio	95%CI
When the mean UtA PI was abnormal at the first trimester and then it was normal at the second and/or third trimesters	0.95	0.31–1.89
When the mean UtA PI was abnormal at the first trimester and then it was normal at the second trimester	0.92	0.21–0.99
When the mean UtA PI was abnormal at the first and second trimesters and then it was normal at the third trimester	0.96	0.19–0.98
When the mean UtA PI was abnormal at the first trimester and then it was normal at the third trimester	0.67	0.38–1.16
No ASA intake or started it after 14 weeks of gestation	1.62	0.87–3.01

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[1] Address for correspondence
Ximena Romero Infante, MD, Universidad El Bosque, Av. Carrera 9 # 131a-02. 110121000, Ecodiagnóstico El Bosque S. A. S, Calle 134 # 7B - 83, Bogotá, Colombia (e-mail: romeroximena@unbosque.edu.co).