Is the Relationship between Short Interpregnancy Interval and Preterm Birth Related to a Short Cervix?

Abstract

Objective Our objective was to determine if the relationship between interpregnancy interval (IPI) and preterm delivery was related to cervical shortening.

Methods This is a secondary analysis of a prospective cohort study designed to assess the relationship between cervical length (CL) and preterm delivery. Multiparous patients, who had transvaginal CLs obtained at 22 to 24 weeks and complete pregnancy outcome data available were included. The women were divided into two groups: Group 1 with an IPI of ≤ 1 year and Group 2 with an IPI of > 1 year. The primary outcome was short cervix (CL < 2.5 cm) at 24 weeks. The secondary outcome was the incidence of preterm delivery < 37 weeks. Interaction between short cervix and IPI was examined in a regression model.

Results There were 155 women in Group 1 and 328 women in Group 2. There was no difference in the incidence of short cervix between groups (10.0% in Group 1 and 12.9% in Group 2, p = 0.35). In a logistic regression model, short IPI and short cervix were independently associated with preterm birth.

Conclusion The relationship between short IPI and preterm birth is not explained by a short cervix. They remain independent risk factors for preterm birth.

Keywords

interpregnancy interval - short cervix - preterm birth - cervical length

Note

This study was presented at the 63rd Annual Meeting of the Society for Reproductive Investigation in Montreal, Canada, Abstract #949.

• References

• 1 HHS. Healthy People 2020: Family planning objectives. Available at: http://www.healthypeople.gov/2020/topicsobjectives2020/objectives list.aspx?topicId=13 . Accessed Feb 2016
• 2 Conde-Agudelo A, Rosas-Bermúdez A, Kafury-Goeta AC. Birth spacing and risk of adverse perinatal outcomes: a meta-analysis. JAMA 2006; 295 (15) 1809-1823
• 3 Copen CE, Thoma ME, Kirmeyer S. Interpregnancy intervals in the United States: data from the birth certificate and the National Survey of Family Growth. Natl Vital Stat Rep 2015; 64: 1-10
• 4 Doyle W, Srivastava A, Crawford MA, Bhatti R, Brooke Z, Costeloe KL. Inter-pregnancy folate and iron status of women in an inner-city population. Br J Nutr 2001; 86 (01) 81-87
• 5 King JC. The risk of maternal nutritional depletion and poor outcomes increases in early or closely spaced pregnancies. J Nutr 2003; 133 (05) (Suppl. 02) 1732S-1736S
• 6 Miller JE. Birth intervals and perinatal health: an investigation of three hypotheses. Fam Plann Perspect 1991; 23 (02) 62-70
• 7 van Eijsden M, Smits LJ, van der Wal MF, Bonsel GJ. Association between short interpregnancy intervals and term birth weight: the role of folate depletion. Am J Clin Nutr 2008; 88 (01) 147-153
• 8 Conde-Agudelo A, Rosas-Bermudez A, Castaño F, Norton MH. Effects of birth spacing on maternal, perinatal, infant, and child health: a systematic review of causal mechanisms. Stud Fam Plann 2012; 43 (02) 93-114
• 9 Iams JD, Goldenberg RL, Meis PJ. , et al; National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network. The length of the cervix and the risk of spontaneous premature delivery. N Engl J Med 1996; 334 (09) 567-572
• 10 Haaga JG. How is birth spacing related to infant health?. Malays J Reprod Health 1988; 6 (02) 108-120
• 11 Sundtoft I, Sommer S, Uldbjerg N. Cervical collagen concentration within 15 months after delivery. Am J Obstet Gynecol 2011; 205 (01) 59.e1-59.e3
• 12 Subramaniam A, Wetta LL, Owen J. Relationship between interpregnancy interval and cervical length in high-risk women. J Matern Fetal Neonatal Med 2016; 29 (08) 1205-1208