Height below 154 cm is a risk factor for pulmonary edema in twin pregnancy: An observational study

Abstract

Twin pregnancies have become more common, leading to an increased focus on associated health risks, including postpartum pulmonary edema (PPE). This study analyzed risk factors for PPE in twin pregnancies using data from the "DATADRYAD" database. Statistical methods such as multivariate logistic regression and smoothed curve fitting were employed to explore the relationship between maternal height and the risk of PPE.

Key findings include:

1. Among women shorter than 154 cm, the risk of developing PPE decreased as height increased (OR = 0.65, P = 0.0104).
2. For women taller than 154 cm, no significant relationship between height and PPE risk was observed (P = 0.9142).
3. Overall, women taller than 154 cm had a 76% lower risk of PPE compared to those shorter than 154 cm (P = 0.0005).

Methods

Data Sources

Data were sourced from the "DATADRYAD" database (www.DATADRYAD.org; https://doi.org/10.5061/dryad.1v8v6). The dataset included variables such as maternal characteristics (age, height, weight, BMI), pregnancy details (gestational age, monochorionic status, assisted reproductive technology), delivery outcomes (cesarean delivery, birth weights), and postpartum factors (pulmonary edema, hemorrhage, transfusions, medication usage).

Study Population

This retrospective study analyzed data from 233 women with twin pregnancies who delivered between September 2009 and November 2016 at Central Hospital, Yamanashi Prefecture, Japan. Exclusion criteria included cases of singleton or twin death, severe fetal malformations, or double arterial perfusion sequences.

Statistical Analysis

Statistical analysis was conducted using R (version 3.6.3) and Empower Stats (version 4.2). Categorical variables were analyzed with chi-square tests, and continuous variables with regression models. Three models assessed the correlation between maternal height and postpartum pulmonary edema, adjusting for various confounders. Smoothed curve fitting and generalized additive models further refined the analysis, with statistical significance set at P < .05.

Result

Twin pregnancies with height below 154 cm, the lower the height the more likely to get pulmonary edema

This study analyzed the relationship between maternal height and postpartum pulmonary edema, treating height as a continuous variable. After adjusting for multiple factors, the inflection point was identified at 154 cm (likelihood ratio = 0.037). Below this threshold, the risk of pulmonary edema decreased with increasing height (OR = 0.65, P = .0104). Above 154 cm, no significant relationship was observed (P = .9142). Smoothed curve fitting confirmed these findings, showing a consistent trend with the threshold and saturation effect analyses.

Incidence of Pulmonary Edema in Twin Pregnancies Below 154 cm

The study included 226 twin pregnancies, with 46 women under 154 cm in height and 180 over 154 cm. Women under 154 cm had a lower mean weight (46.79 kg vs. 55.35 kg, P < .001) and a significantly higher incidence of postpartum pulmonary edema (30.43% vs. 9.44%, P < .001). Magnesium-containing fluids were administered more frequently to shorter women (18 vs. 29 cases, P < .001), and there was a statistically significant difference in total fetal weight (P = .046). 

Lower Risk of Pulmonary Edema in Women Taller Than 154 cm

Univariate analysis showed that pregnant women with twin pregnancies taller than 154 cm had a 76% lower risk of postpartum pulmonary edema compared to those shorter than 154 cm (P = .0005).

Other factors reducing the risk of pulmonary edema included:

• Bed rest <6 weeks: OR = 0.28 (72% lower risk), P = .0056.
• Absence of gestational hypertension: OR = 0.31 (69% lower risk), P = .0104.
• No postpartum hemorrhage: OR = 0.26 (74% lower risk), P = .015.

Discussion

Pulmonary edema during pregnancy and postpartum is a severe complication and a significant manifestation of acute heart failure. It results from excess fluid accumulation in the lungs, impairing gas exchange and potentially leading to hypoxemia, brain damage, or even death if untreated. Though rare, pulmonary edema is associated with high maternal mortality, especially in twin pregnancies.

This study identified maternal height as a risk factor for postpartum pulmonary edema, with a threshold of 154 cm. Women shorter than 154 cm had a higher risk of developing pulmonary edema, which increased as height decreased. Twin pregnancies pose additional cardiovascular challenges compared to singleton pregnancies, such as greater blood volume, increased cardiac output, and reduced vascular resistance, which can strain maternal heart function. These physiological changes, combined with mechanical factors like inferior vena cava compression and reduced lung expansion, elevate the risk of pulmonary edema in shorter women.

The findings highlight the importance of monitoring and preparing for potential complications in twin pregnancies, particularly for women under 154 cm. Physicians should assess the suitability of twin pregnancies in this group and implement early preventive measures during delivery.

Limitations of this study include its cross-sectional design, reliance on public database data, and the potential influence of unaccounted confounding factors. Further prospective studies with larger, more diverse populations are needed to confirm these findings.

Conclusion

Our research shows that twin pregnancies with heights below 154 cm are more likely to develop pulmonary edema after delivery, and the lower the height, the greater the risk. Therefore, healthcare professionals and caregivers should pay closer attention to twin pregnancies with heights below 154 cm, be alert to the development of pulmonary edema, and take preventive measures and treatments as early as possible. This will help prevent the development of postpartum pulmonary edema.

Source

Wan, Bingen MDa; Hu, Sheng MDa; Wang, Silin MDa; Wei, Yiping PhD, MDa; Xu, Jianjun PhD, MDa; Zheng, Qiaoling MDb,*. Height below 154 cm is a risk factor for pulmonary edema in twin pregnancy: An observational study. Medicine 103(45):p e40312, November 08, 2024. | DOI:10.1097/MD.0000000000040312