The Relationship between Use of Low Molecular Weight Heparin during Pregnancy and Risk of Peripartum Adverse Events: A Meta-Analysis

Research Article

Ann Hematol Oncol. 2021; 8(11): 1372.

The Relationship between Use of Low Molecular Weight Heparin during Pregnancy and Risk of Peripartum Adverse Events: A Meta-Analysis

Xiaorong Y1#, Shan L2#, Shengji S1,2#, Tao S2, Dongping L3, Moli Z4* and Junping L3*

1Department of Rehabilitation, Chengdu Women’s and Children’s Central Hospital, Affiliated Hospital of Medical College, University of Electronic Science and technology, Sichuan, China

2Department of Cardiology, Huashan Hospital, Fudan University, Shanghai, China

3Department of Gynaecology and Obstetrics, Huahsan Hospital North, Fudan University, Shanghai, China

4Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China

#Contributed Equally to this Work

*Corresponding author: Li Junping, Department of Gynaecology and Obstetrics, Huahsan Hospital North, Fudan University, No. 518 jingbohu Road, Shanghai, China

Zhu Moli, Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China

Received: July 27, 2021; Accepted: August 28, 2021; Published: September 04, 2021


Introduction: To summarize the trials investigated on relationship between low molecular weight heparin use during pregnancy and peripartum adverse events. Meta-analysis was performed to evaluate the effect of Low Molecular Weight Heparin (LMWH) on maternal and fetal complications.

Methods: Electronic research was performed in Cochrane Library, MEDLINE and EMBASE through October 2020. The primary outcome was the incidence of maternal and fetal complications during peripartum period. RevMan 5.3 was used for data analysis.

Results: 11 articles were finally included. Meta-analysis showed there was no significant difference in abortion, premature delivery, stillbirth, preeclampsia and postpartum hemorrhage events between pregnant women who used LMWH and those who not.

Conclusion: Using LMWH in pregnant women does not increase pregnancy related maternal and fetal complications.

Keywords: Low molecular weight heparin; Postpartum adverse events; Gestation


The risk of thromboembolic diseases is significantly increased during pregnancy, particularly Deep Venous Thrombosis (DVT) and Pulmonary Embolism (PE). Venous Thromboembolism (VTE) is the main cause of maternal death during pregnancy, while pulmonary embolism is a common cause of maternal death in developed countries [1]. Although the overall risk of VTE events is low, pregnant women are five times more likely to develop VTE events than non-pregnant women of the same age [2]. Many scholars believe that this is caused by venous stasis due to the oppression of pregnant uterus and the imbalance of bleeding and coagulation status during pregnancy [3-5]. Common risk factors for venous thrombosis in pregnant women include age over 35, obesity, multiple pregnancies, genetic susceptibility, surgery or cesarean section, smoking and hormone therapy, pregnancy related diabetes, placental abruption and eclampsia [6]. Hospitalization before or after delivery may also increase the risk of VTE events. Besides, Women with a history of venous thrombosis before pregnancy also have an increased risk of recurrent venous thrombosis during pregnancy [7,8]. Low Molecular Weight Heparin (LMWH) is currently the preferred drug for the prevention or treatment of venous thrombosis in pregnant women. LMWH does not cross the placenta and has a more stable anticoagulant effect with a longer half-life and greater bioavailability [9]. LMWH allows daily subcutaneous administration and does not need laboratory monitoring. With the increased use of LMWH in pregnant women and relevant experience accumulation, the worrisome of the effectiveness and safety of LMWH during peripartum period is also increasing. Whether the use of LMWH in pregnant women increases peripartum adverse events in still debatable. Therefore, we did this work to analyze the relationship between use of LMWH during pregnancy and risk of peripartum adverse events, hoping to provide some guidance for the drug use.


Inclusion criteria

1) Pregnant women who received anticoagulant therapy with LMWH; 2) Anticoagulant therapy is maintained at least 6 weeks postpartum; 3) Study endpoints included pregnancy-related maternal and fetal complications.

Exclusion criteria

1) Combined use of other types of anticoagulants; 2) LMWH was used prior to pregnancy; 3) Studies not included pregnant women who use placebo or did not use anticoagulant drugs as control group; 4) Pregnant women had heparin induced thrombocytopenia; 5) Case reports.

Evaluation of efficiency

In our study, pregnancy related maternal and fetal complications were taken as the primary endpoints. Pregnancy related maternal and fetal complications included abortion, premature delivery, stillbirth, preeclampsia, fetal growth restriction, and postpartum hemorrhage. Postpartum hemorrhage was defined as the blood loss of 500mL or more during natural labour, and 1000mL or more during cesarean section.

Search strategy

We performed electronic research in Cochrane Library, MEDLINE, EMBASE, CQVIP, CNKI and Wanfang Database through October 2020 with the use of a combination of text words related to “heparin”, “low molecular weight heparin”, “LMWH”, “Anticoagulant drug”, “postpartum OR stegmonth OR puerperium” and “complication”. No restrictions for language or geographic location were applied.

Methods of literature quality evaluation

All the studies included were non-randomized controlled trials. And the MINORS Scale was used to evaluate the study quality. The features of the included literatures and research objects are shown in Table 1 and 2.