The Effects of Interpregnancy Intervals and Previous Pregnancy Outcome on Fetal Loss in Rwanda (1996–2010)

Table 4

(a) Results from other studies concerning the effect of IPI duration on pregnancy loss after a previous spontaneous or induced termination. (b) Results from studies concerning the effect of IPI duration on pregnancy loss after various previous pregnancy outcomes.

(a)

Study; period/country	Sample	Effect of IPI	Reference category for statistical analysis	Controlled for
Wong et al. 2015 [6]; USA (EAGeR trial) period 2006–2012	724 pregnant women with 1-2 prior pregnancy losses	No association between adverse pregnancy outcomes including pregnancy loss and IPI (<3 months or > 3 months)	Unknown	Demographic and reproductive history characteristics
Makhlouf et al. 2014 [7]; USA, period 2003–2008	Nulliparous women; 7681 primigravida; 1240 with 1-2 previous spontaneous pregnancy losses (SAB); 817 with a previous induced abortion (IAB)	On fetal/neonatal death and other adverse outcomes after SAB and IAB; No statistically significant difference for various IPI (<6, 6–12, >12 months) on risk of fetal loss and neonatal death	Primigravida; Women with one previous SAB and IPI < 6 months	Maternal age, race, education, smoking, marital status, BMI, and use of vitamins C and E
DaVanzo et al. 2012 [4]; Bangladesh (Matlab), period 1977–2008	9214 women with a miscarriage (spontaneous abortion prior to gestation of 28 weeks)	The shorter the IPI following a miscarriage is, the more likely the next pregnancy results in a live birth; No significant effects of IPI duration on risks of a stillbirth Relative risk of a subsequent miscarriage increases with IPI duration	Women with a previous miscarriage and IPI of 6–12 months	Maternal age, education, gravidity, and calendar year
Love et al. 2010 [5]; Scottish hospital data, period 1981–2000	30,937 women with a miscarriage in first recorded pregnancy	On miscarriage, ectopic pregnancy, IAB, and stillbirth; Women with IPI < 6 months had less likely a miscarriage, highest sign Risk for women with IPI > 24 months; No significant effect of IPI duration on risk of stillbirth	Women with a miscarriage and IPI of 6–12 months	Maternal age, socioeconomic status, year of first conception, and smoking
Conde-Agudelo et al. 2005 [9]; Latin America period 1985–2002	258,108 women with a previous abortion	On fetal death and other adverse outcomes; No significant difference of effect of IPI on fetal death or on neonatal death	Women with an IPI of 18–23 months	Maternal age, parity, education, smoking, marital status, BMI, year of delivery, hypertension, nbr antenatal checks, hospital type, and geographical area

IPI = interpregnancy interval, SAB = spontaneous abortion, IAB = induced abortion, and BMI = Body Mass Index.

(b)

Study	Sample	Effect of IPI	Reference category	Controlled for
Conde-Agudelo et al. 2006 [3]; Rich and poor countries from all over the world	Meta-analysis	On various adverse perinatal outcomes; Less clear is the association between pregnancy spacing and the risk of fetal (and neonatal) death Curves suggest that IPI < 6 months and IPI > 50 months are associated with increased risks	Differs per included study	Various factors; Not standard for previous pregnancy outcome
DaVanzo et al. 2007 [11]; Bangladesh (Matlab); period 1982–2002	66759 pregnancies including multiple births of 28540 women	On various pregnancy outcomes; An IPI < 6 months after a live birth lead to a 7.5 fold increase for miscarriages, and 1.6 fold increase for stillbirths. An IPI >75 months showed a less increased risk on fetal losses.; After a fetal loss a higher likelihood of a subsequent same fetal loss regardless of the IPI duration; Highest OR on a miscarriage after IPI < 6 months after a life birth	Women with live birth after IPI of 27–50 months	Socioeconomic status, maternal age, education both spouses, religion, and calendar year
Stephansson et al. 2003 [12]; Sweden, period 1983–1997	410,021 women with two deliveries	Stillbirths and early neonatal death; Previous reproductive history and maternal characteristics substantially confounded the association between IPI and risks of stillbirth; Risks are only found for long intervals; Role of short intervals may have been overestimated in previous studies	IPI of 12–35 months	Outcome of first pregnancy (stillbirth/early neonatal death, preterm delivery, etc.) Maternal age, education, presence of partner, country of origin, diabetes, hypertension, period of delivery, and smoking