Studies - PreTerm Delivery / Premature Birth / Prematurity Complications

7 Studies: Abortion and Subsequent Risk of Preterm Delivery (1993-2005)

Abortion and Subsequent Premature Birth (3/05)

There are over 40 studies that demonstrate a statistically significant association between abortion and subsequent premature birth, especially extreme premature birth (XPB): 

1993 Study:

An Australian study by Lumley in l993 showed that having 3 abortions (mostly suction) is associated with a risk ratio of 5.6 for XPB (22-28 wks) (data base 121,000 deliveries).

Reduce Preterm Risk Coalition Comments:

Extremely preterm newborn (<28 weeks' gestation) have about THIRTY-EIGHT (38) times the risk of CP (Cerebral Palsy) as the general population of newborn. 

In 1993 the truly great Australian preterm birth expert Judith Lumley reported that prior induced abortions boosted the risk of EXTREMELY newborn; one prior IA boosted relative XPB risk by 55% and two prior IAs boosted XPB risk by 146%.

(Lumley J. The epidemiology of preterm birth. Bailliere's Clin Obstet Gynecology.1993;7(3):477-498) [comments by Brent Rooney, Reduce Preterm Risk Coalition, Vancouver, Canada www.jpands.org/vol8no2/rooney.pdf]

 

1998 Studies:

Dr. DeCook: 
In 1998, (data base of 243,000 deliveries), Lumley showed that 4 or more IAs [induced abortions] had a risk increase of 9 fold-NINE times the primagravida controls. 

A 1998 study from Bavaria (data base 106,000) showed, for less than 32 wk deliveries, a RR of 2.5 after 1 abortion, 5.2 after 2 abortions, and 8.0 after 3 abortions. 

1999 Study:

A 1999 Danish study showed that a D&E [abortion] increased the risk of PTB [Pre-Term Birth] substantially:  after 1 D&E , RR 2.2,; after 2 D&Es, RR 12.5.

2002 Thorpe Study:

The Thorpe study (Jan 2002, OB GYN Survey) noted 12 studies finding an association between IA and PTB, with an "increased risk of very early deliveries at 20 to 30 weeks gestation after induced abortion…"

2004 Study:

The Europop study (in Human Reproduction, Jan, 2004) concludes:  Previous induced abortions were significantly associated with preterm delivery and the risk of preterm birth increased with the number of abortions. (data base 2939 PTB, 4881 controls).

2005 (Published) Study:

And now a French study (in Brit J of Ob&Gyn,  Online early abstract) concludes:  Women with a history of induced abortion were at higher risk of very preterm delivery – under 33 wk – than those with no such history (OR 1.5).  The risk was even higher for XPB – under 28
wk (OR not mentioned).  A history of induced abortion was associated with an increased risk of PROM, antepartum hemorrhage, and idiopathic spontaneous preterm labor.

[Joe  DeCook, MD, for AAPLOG, 25Mar05]

2005 Study Abstract

BJOG: An International Journal of Obstetrics & Gynaecology
OnlineEarly
doi:10.1111/j.1471-0528.2004.00478.x
Previous induced abortions and the risk of very preterm delivery: results of the EPIPAGE study
Caroline Moreaua, Monique Kaminskia, Pierre Yves Ancela, Jean Bouyerb, Benoît Escandec, Gérard Thiriezd, Pierre Boulote, Jeanne Fressonf, Catherine Arnaudg, Damien Subtilh, Loic Marpeaui, Jean-Christophe Rozéj, Françoise Maillarda, Béatrice Larroquea, EPIPAGE Group

To evaluate the risk of very preterm birth (22-32 weeks of gestation) associated with previous induced abortion according to the complications leading to very preterm delivery in singletons.

Design:  Multicentre, case-control study (the French EPIPAGE study).

Setting:  Regionally defined population of births in France.

Sample:  The sample consisted of 1943 very preterm live-born singletons (<33 weeks of gestation), 276 moderate preterm live-born singletons (33-34 weeks) and 618 unmatched full-term controls (39-40 weeks).

Methods:  Data from the EPIPAGE study were analysed using polytomous logistic regression models to control for social and demographic characteristics, lifestyle habits during pregnancy and obstetric history. The main mechanisms of preterm delivery were classified as gestational hypertension, antepartum haemorrhage, fetal growth restriction, premature rupture of membranes, idiopathic preterm labor and other causes.

Main outcome measures:  Odds ratios for very preterm birth by gestational age and by pregnancy complications leading to preterm delivery associated with a history of induced abortion.

Results:  Women with a history of induced abortion were at higher risk of very preterm delivery than those with no such history (OR + 1.5, 95% CI 1.12.0); the risk was even higher for extremely preterm deliveries (<28 weeks). The association between previous induced abortion and very preterm delivery varied according to the main complications leading to very preterm delivery.

A history of induced abortion was associated with an increased risk of premature rupture of the membranes, antepartum haemorrhage (not in association with hypertension) and idiopathic spontaneous preterm labour that occur at very small gestational ages (<28 weeks). Conversely, no association was found between induced abortion and very preterm delivery due to hypertension.

Conclusion:  Previous induced abortion was associated with an increased risk of very preterm delivery. The strength of the association increased with decreasing gestational age.

Comments from Reduce Preterm Risk Coalition:

This is the first study ever in Europe (French women) or the U.S. of the XPB risk of IAs (Induced Abortions). It confirms Lumley's finding (1993 study below).
Here is an excerpt from an abstract in the highly respected British
Journal of Obstetrics and Gynaecology (above):

     "Results: Women with a history of induced abortion were at a
     higher risk of very preterm [<33 weeks' gestation] delivery
     than those with no such history (OR: 1.5, 95% CI 1.1-2.0);
     [OR= 1.5 is a 50% boost in relative risk] the risk was even
     higher for extremely preterm (<28 weeks)."


     Full abstract:

www.blackwell-synergy.com/links/doi/10.1111/j.14710528.2004.00478.x/abs/

or, do a 'Google' search: "extremely preterm" "induced abortion" entry: "www.blackwell-synergy".

     According of the UK Life League, the full study should be published in March 2005 in the British Journal of Obstetrics and Gynaecology.