Practice Advisory: Influenza Vaccination During Pregnancy

A September 2017 case-control study published in the journal Vaccine reported a possible association between influenza (flu) vaccination when given early in the first trimester and spontaneous abortion(1). In this study, women who experienced miscarriage in early pregnancy had an increased odds ratio of having received influenza vaccine in the preceding 28 days.  There was no association seen with a pregnancy loss more than 28 days after vaccination. In the same study, when vaccination was given either later in the first trimester or in the second or third trimester, there was no association seen with pregnancy loss or any other adverse pregnancy outcomes. It is important to note that this study has major limitations and should not be interpreted as scientific support for a causal relationship between influenza vaccination and spontaneous abortion(1).  Additional studies are needed to address the concerns raised by this study.

Pregnant women are at high risk for complications of influenza including serious illness, hospitalization, and death(2). Maternal influenza vaccination has been shown to decrease the risk of influenza and its complications among pregnant women and their infants in the first 6 months of life. The safety of vaccines used during pregnancy is a critical concern for ob-gyns and their patients. The American College of Obstetricians and Gynecologists (ACOG) monitors pregnancy-related vaccine safety information through its collaborations with the National Vaccine Advisory Committee (NVAC) through the U.S. Department of Health & Human Services (HHS) and with the Advisory Committee on Immunizations Practices (ACIP) through the Centers for Disease Control and Prevention (CDC). For many years, ACOG and the CDC have recommended that every pregnant woman receive a flu shot during any trimester(3,4). Multiple published studies, as well as clinical experience, have supported this position that the flu vaccine is safe and effective during pregnancy(5-9).  

In evaluating all the available scientific information, the results from the September 2017 study do not warrant changing the current recommendation. Influenza vaccination remains the best available prevention for serious morbidity related to flu in pregnancy. Therefore, ACOG recommends that ob-gyns continue to encourage routine flu vaccination during pregnancy in any trimester. 

For more information on the safety of influenza vaccination during pregnancy visit ACOG’s Immunization for Women website and CDC’s website.


1. Donahue JG, Kieke BA, King JP, DeStefano F, Mascola MA, Irving SA, et al. Association of spontaneous abortion with receipt of inactivated influenza vaccine containing H1N1pdm09 in 2010-11 and 2011-12. Vaccine 2017;35:5314-22. Available at: Retrieved November 17, 2017. 

2. Rasmussen SA, Jamieson DJ. 2009 H1N1 influenza and pregnancy--5 years later. N Engl J Med 2014;371:1373-5. Available at: Retrieved November 17, 2017. 

3. Influenza vaccination during pregnancy. Committee Opinion No. 608. American College of Obstetricians and Gynecologists. Obstet Gynecol 2014;124:648-51. Available at: Retrieved November 17, 2017.

4. Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Bresee JS, Fry AM, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices - United States, 2017-18 influenza season. MMWR Recomm Rep 2017;66(RR-2):1-20. Available at: Retrieved November 17, 2017. 

5. Prevention and control of seasonal influenza with vaccines. Recommendations of the Advisory Committee on Immunization Practices--United States, 2013-2014. Centers for Disease Control and Prevention (CDC) [published erratum appears in MMWR Morb Mortal Wkly Rep 2013;62:906]. MMWR Recomm Rep 2013;62(RR-7):1-43. Available at: Retrieved November 17, 2017.

6. Tamma PD, Ault KA, del Rio C, Steinhoff MC, Halsey NA, Omer SB. Safety of influenza vaccination during pregnancy. Am J Obstet Gynecol 2009;201:547-52. Available at: Retrieved November 17, 2017.

7. Carcione D, Blyth CC, Richmond PC, Mak DB, Effler PV. Safety surveillance of influenza vaccine in pregnant women. Aust N Z J Obstet Gynaecol 2013;53:98-9. Available at: Retrieved November 17, 2017.

8. Moro PL, Broder K, Zheteyeva Y, Walton K, Rohan P, Sutherland A, et al. Adverse events in pregnant women following administration of trivalent inactivated influenza vaccine and live attenuated influenza vaccine in the Vaccine Adverse Event Reporting System, 1990-2009. Am J Obstet Gynecol 2011;204:146.e1-7. Available at: Retrieved November 17, 2017. 

9. Bednarczyk RA, Adjaye-Gbewonyo D, Omer SB. Safety of influenza immunization during pregnancy for the fetus and the neonate. Am J Obstet Gynecol 2012;207:S38-46. Available at: Retrieved November 17, 2017.

This Practice Advisory was developed by the American College of Obstetricians and Gynecologists in collaboration with Laura E. Riley, MD, Rhoda Sperling, MD, and Joseph Wax, MD.

A Practice Advisory is issued when information on an emergent clinical issue (e.g. clinical study, scientific report, draft regulation) is released that requires an immediate or rapid response, particularly if it is anticipated that it will generate a multitude of inquiries. A Practice Advisory is a brief, focused statement issued within 24-48 hours of the release of this evolving information and constitutes ACOG clinical guidance. A Practice Advisory is issued only on-line for Fellows but may also be used by patients and the media. Practice Advisories are reviewed periodically for reaffirmation, revision, withdrawal or incorporation into other ACOG guidelines. 

This information is designed as an educational resource to aid clinicians in providing obstetric and gynecologic care, and use of this information is voluntary. This information should not be considered as inclusive of all proper treatments or methods of care or as a statement of the standard of care. It is not intended to substitute for the independent professional judgment of the treating clinician. Variations in practice may be warranted when, in the reasonable judgment of the treating clinician, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology. The American College of Obstetricians and Gynecologists reviews its publications regularly; however, its publications may not reflect the most recent evidence. Any updates to this document can be found on or by calling the ACOG Resource Center.

While ACOG makes every effort to present accurate and reliable information, this publication is provided “as is” without any warranty of accuracy, reliability, or otherwise, either express or implied. ACOG does not guarantee, warrant, or endorse the products or services of any firm, organization, or person. Neither ACOG nor its officers, directors, members, employees, or agents will be liable for any loss, damage, or claim with respect to any liabilities, including direct, special, indirect, or consequential damages, incurred in connection with this publication or reliance on the information presented.

Publications of the American College of Obstetrician and Gynecologists are protected by copyright and all rights are reserved. The College's publications may not be reproduced in any form or by any means without written permission from the copyright owner. 

The American College of Obstetricians and Gynecologists (The College), a 501(c)(3) organization, is the nation's leading group of physicians providing health care for women. As a private, voluntary, nonprofit membership organization of more than 57,000 members, The College strongly advocates for quality health care for women, maintains the highest standards of clinical practice and continuing education of its members, promotes patient education, and increases awareness among its members and the public of the changing issues facing women’s health care. The American Congress of Obstetricians and Gynecologists (ACOG), a 501(c)(6) organization, is its companion organization.

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