Premature Birth May Induce Variability in the Mother's Systolic Blood Pressure

Pregnancy-related complications, such as gestational diabetes, preeclampsia, intrauterine growth retardation, are known to impact a woman’s cardiovascular functioning. However, the exact link between these associations remain unknown.

The authors of the current study included nearly 2000 pregnant women who were evaluated to identify whether premature birth (PTB) leads to variability in long-term systolic blood pressure (SBP).¹ The 1974 women in the study, who had given birth between 1976 and 2007 in a single hospital in China, were divided into 2 groups: PTB (n = 111) and non-PTB (n = 1863). Those who had complete delivery records and had 4 annual medical examinations on record were included. Exclusion criteria included stroke, myocardial infarction, missing data on gestational weeks, and missing data on blood pressure.

While blood pressure variability, such as hypertension, has been known to lead to cardiovascular and cerebral damage, research has found that women are more sensitive to these fluctuations.²

Data collection in this study was through a survey that enquired on the delivery time and name of hospital where the pregnant women were enrolled; medical information from the women’s records were entered by staff, who also collected epidemiological information through an interview with the participants and included information on personal and family history of diagnosed disease conditions. Participant blood pressure was measured by the physicians and blood samples were analyzed for total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and fasting blood glucose (FBG).

With an age range of 23 to 69 years (median, 38 years) at the time of the annual examination between 2006 and 2007, the log-transformed TG and pregnancy-induced hypertension (PIH) in the PTB group was much higher than the non-PTB group (P <.05); TC, HDL, and FBG showed a trend to be lower in the PTB group but was not significant.

The analyses found that SBP standard deviation (SSD) as well as the SBP coefficient of variation (SCV) were higher for PTB (10.95 mmHg and 9.05%, respectively), compared with the non-PTB group (9.81 mmHg and 8.23%, respectively), but these differences were not significant. A significantly (P <.05) higher percentage of patients in the PTB group had SSD >9.87 mmHg (51.40%) and SCV >8.28% (55.90%) compared with the non-PTB group (40.10% and 45.10%, respectively).

Logistic regression on their cohorts confirmed that the PTB group was at a risk of SSD and SCV elevations: PTB was a risk factor for SSD ≥9.87 mmHg, by assigning PTB as the independent variable (Model 1) (odds ratio [OR], 1.58; 95% CI, 1.08—2.31; P <.05), by adjusting age and body-mass index based on Model 1 (Model 2) (OR, 1.55; 95% CI, 1.04—2.31; P <.05), or by adjusting TC, HDL, FBG, TG, and PIH based on Model 2 (Model 3) (OR, 1.60; 95% CI, 1.06—2.40; P <.05). Similarly, PTB was a risk factor for SCV in Model 1 (OR, 1.55; 95% CI, 1.06—2.29; P <.05), Model 2 (OR, 1.55; 95% CI, 1.05—2.29; P <.05), and Model 3 (OR, 1.64; 95% CI, 1.00—2.45; P <.05).

“Pregnancy may provide an opportunity to identify women at an increased risk of [cardiovascular disease] relatively early in life,” the authors conclude based on their findings.

References

1. Shi L, An S, Niu J, Zhao H, Wang Y, Wu S, Yang X. Effect of premature birth on long-term systolic blood pressure variability in women. Anatol J Cardiol. 2018;20(6):347-353. doi: 10.14744/AnatolJCardiol.2018.97415.
2. Muntner P, Shimbo D, Tonelli M, Reynolds K, Arnett DK, Oparil S. The relationship between visit-to-visit variability in systolic blood pressure and all-cause mortality in the general population: findings from NHANES III, 1988 to 1994. Hypertension. 2011;57(2):160-166. doi: 10.1161/HYPERTENSIONAHA.110.162255.