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CSU 72/2009: BIRTH INTERVALS AND MDG 5/ THE VATICAN VIEW ON BIRTH SPACING

Friday, 13th of November 2009

CSU 72/2009: BIRTH INTERVALS AND MDG 5/  THE VATICAN VIEW ON BIRTH SPACING
 
 Do I err in believing that there is no UN policy endorsement of birth
 spacing as a way of more rapidly achieving MDG 4 and MDG 5? Is this not a
 remarkable omission when most countries are lagging in their progress
 towards cutting under five and maternal mortality?
 
 
 1) RESEARCH WORK OF CONDE-AGUDELO
 
 The present paper is truly ground breaking, and has been cited in 10 other
 papers.
 
 Can countries which have thus far failed to reduce maternal mortality
 succeed in moving towards MDG 5 by lengthening of unduly short birth
 intervals?
 
 Also at  http://www.bmj.com/cgi/content/full/321/7271/1255?view=long&pmid=11082085
 
 2) THE VATICAN VIEW ON BIRTH SPACING
 
 Since it is rarely quoted correctly, I reproduce the relevant text from
 Humanae Vitae, the 1968 encyclical letter of Pope Paul VI. Latinists need
 not skip to the translation.
 
 Si igitur iustae adsint causae generationes subsequentes intervallandi,  quae a coniugum corporis vel animi condicionibus, aut ab externis rerum  adiunctis proficiscantur, Ecclesia docet, tunc licere coniugibus sequi  vices naturales, generandi facultatibus immanentes, in maritali commercio  habendo iis dumtaxat temporibus, quae conceptione vacent, atque adeo  nasciturae proli ita consulere, ut morum doctrina, quam modo exposuimus,  haudquaquam laedatur.(20)
 
 If therefore there are well-grounded reasons for spacing births, arising  from the physical or psychological condition of husband or wife, or from  external circumstances, the Church teaches that married people may then  take advantage of the natural cycles immanent in the reproductive system
 and engage in marital intercourse only during those times that are  infertile, thus controlling birth in a way which does not in the least  offend the moral principles which We have just explained. (20)
 
  
 Good reading.
 
 BD
 
 
 BMJ 2000;321:1255-1259 ( 18 November )
 Papers
 Maternal morbidity and mortality associated with interpregnancy interval:
 cross sectional study
 
 
 Agustin Conde-Agudelo, perinatal researcher, José M Belizán, director.
 
 
 Latin American Centre for Perinatology and Human Development (CLAP),
 Division of Health Promotion and Protection, Pan American Health
 Organisation, World Health Organisation, Montevideo, Uruguay
 
 
 Correspondence to: A Conde-Agudelo condeagu@uniweb.net.co
  
 Objective: To study the impact of interpregnancy interval on maternal
 morbidity and mortality.
 

Design: Retrospective cross sectional study with data from the Perinatal
 Information System database of the Latin American Centre for Perinatology
 and Human Development, Montevideo, Uruguay.

 Setting: Latin America and the Caribbean, 1985-97.

 Participants: 456 889 parous women delivering singleton infants.
 Main outcome measures: Crude and adjusted odds ratios of the effects of
 short and long interpregnancy intervals on maternal death, pre-eclampsia,
 eclampsia, gestational diabetes mellitus, third trimester bleeding,
 premature rupture of membranes, postpartum haemorrhage, puerperal
 endometritis, and anaemia.

 Results: Short (<6 months) and long (59 months) interpregnancy intervals
 were observed for 2.8% and 19.5% of women, respectively. After adjustment
 for major confounding factors, compared with those conceiving at 18 to
 23 months after a previous birth, women with interpregnancy intervals of
 5 months or less had higher risks for maternal death (odds ratio 2.54; 95%
 confidence interval 1.22 to 5.38), third trimester bleeding (1.73; 1.42 to
 2.24), premature rupture of membranes (1.72; 1.53 to 1.93), puerperal
 endometritis (1.33; 1.22 to 1.45), and anaemia (1.30; 1.18 to 1.43).
 Compared with women with interpregnancy intervals of 18 to 23 months, women
 with interpregnancy intervals longer than 59 months had significantly
 increased risks of pre-eclampsia (1.83; 1.72 to 1.94) and eclampsia (1.80;
 1.38 to 2.32).
 Conclusions: Interpregnancy intervals less than 6 months and longer than
 59 months are associated with an increased risk of adverse maternal
 outcomes.
 
 Both short and long interpregnancy intervals have been found to increase
 the risk of various adverse perinatal outcomes, such as low birth weight,
 preterm delivery, infants small for gestational age, stillbirth, and
 neonatal death.1-5 The effect of interpregnancy interval on maternal
 morbidity and mortality has received less attention. In 1944, Eastman
 examined the effect of the interpregnancy interval, defined as "the
 interval between births," on some maternal outcomes in a cohort of
 5158 parous women.6 He found no association between interpregnancy interval
 and maternal anaemia, postpartum haemorrhage, puerperal fever, and maternal
 mortality. The risk of toxaemia, defined as pre-eclampsia and eclampsia
 with or without chronic hypertension, increased steadily with increasing
 interval between pregnancies. This investigation, however, did not control
 for confounding factors, and the number of women with short intervals was
 small. Since then, few studies have examined the association between
 interpregnancy interval and maternal outcomes.7-9 Two were case-control
 studies that looked only for association between interpregnancy interval
 and maternal mortality and provided apparently contradictory results 7 9 :
 one showed an association whereas the other found no association. The other
 study evaluated the risk of anaemia according to intervals between
 pregnancies.8
 
 
 The Latin American and Caribbean Perinatal Information System database,
 which comprises information on maternal sociodemographic characteristics
 and outcomes of pregnancy, provides an opportunity to study the effects of
 interpregnancy interval on maternal morbidity and mortality.
 
 
 
 The Perinatal Information System database in Montevideo, Uruguay, was
 devised by the Latin American Centre for Perinatology and Human Development
 (CLAP) in 1983.10 Currently, this database is used for over half a million
 births each year. From 1985 to 1997 our database has recorded pregnancies
 of women who were born in Uruguay, Argentina, Peru, Colombia, Honduras,
 Paraguay, El Salvador, Chile, Bolivia, Costa Rica, Panama, Dominican
 Republic, Nicaragua, Brazil, Ecuador, Mexico, Bahamas, and Venezuela.
 
 
 Only parous women delivering singleton infants and whose previous pregnancy
 ended in live birth or fetal death after 19 weeks' gestation were included
 in the study. A complete description of the database has been published
 elsewhere. 11 12 From the first antenatal visit until discharge of both
 mother and neonate, the attending physicians or nurses collect data on
 demographic information, reproductive history, maternal characteristics,
 prenatal care, labour management, maternal complications during pregnancy,
 delivery, and the puerperium, and neonatal outcomes. Data are entered on to
 the database and cleaned on site by a data clerk. Queries on the database
 are checked immediately with the attendant physicians or nurses. Data are
 later sent to the Latin American Centre for Perinatology and Human
 Development, where a further data entry, quality control check, and
 validation is performed.
 
 
 Definitions
 Maternal age was defined as completed years at time of delivery. Mothers'
 education was categorised into none, elementary, secondary, and university.
 Marital status was dichotomised between those who did and did not live with
 their infant's father. Maternal height and weight before pregnancy were
 recorded by recall at the woman's first antenatal visit in centimetres and
 kilograms, respectively. The body mass index (weight (kg)/(height (m)2
 before pregnancy) was categorised as underweight (body mass index <19.8);
 normal (19.8-26.0); overweight (26.1-29.0); and obese (29.0).13
 Information on cigarette smoking was also recorded at the first antenatal
 visit and categorised into smoker and non-smoker.
 
 
 Gestational age was estimated from the date of last menstrual period and
 amended by means of ultrasonography in a quarter of women. Interpregnancy
 interval was defined as the time elapsed between the woman's last delivery
 and the date of the last menstrual period for the index pregnancy.
 Intervals were computed in weeks and then converted to months.
 Interpregnancy intervals were categorised as (Embedded image moved to file:
 pic23259.gif)=<5, 6-11, 12-17, 18-23, 24-59, and (Embedded image moved to
 file: pic30033.gif)= 60 months.
 
 
 Adverse maternal outcomes were classified according to ICD-10
 (international classification of diseases, 10th revision). Pre-eclampsia
 and eclampsia were codes O14 and O15, respectively. Third trimester
 bleeding included placenta praevia with haemorrhage (code O44.1) and
 placental abruption (code O45). Anaemia, premature rupture of membranes,
 gestational diabetes mellitus, postpartum haemorrhage, and puerperal
 endometritis were codes O99.0, O42, O24.4, O72, and O85, respectively.
 
 
 Maternal death was defined as the death of a woman while she was pregnant
 or within 42 days after delivery from any cause related to or aggravated by
 the pregnancy or its management but not from accidental or incidental
 causes.
 
 
 Analysis
 Rates of adverse maternal outcomes were calculated for each interpregnancy
 interval. Estimates of crude odds ratios with 95% confidence intervals were
 computed as measures of association between each interpregnancy interval
 and adverse maternal outcome considered. The interval 18-23 months was used
 as the reference category because this was the interval during which
 maternal death was least likely to occur. Adjusted odds ratios were derived
 through logistic regression models. Multiple logistic regression analysis
 was used to evaluate the association between interpregnancy interval and
 adverse maternal outcomes. The estimates were adjusted for 16 major
 confounding factors.
 
 
 
 
 All analyses were done with the SPSS 8.0 program package (SPSS, Chicago).
 
 A total of 520 689 parous women who delivered singleton infants between
 1985 and 1997 were recorded on our database. The final study population
 included 456 889 women whose records contained complete data on
 interpregnancy interval and adverse maternal outcomes. There were no
 significant differences between the women excluded because of incomplete
 data and those with complete data with regard to maternal age, parity,
 education, and marital status.
 
 
 The median interpregnancy interval was 27 months. Short (<6 months) and
 long (59 months) intervals between pregnancies were observed for 2.8% and
 19.5% of women, respectively. Almost a third of the women had an
 interpregnancy interval of less than 18 months.
 
 
 Table 1 shows the characteristics of the mothers at the index pregnancy
 according to interpregnancy interval. Younger maternal age, history of
 miscarriage, fetal death and early neonatal death, lower rate of previous
 caesarean delivery, later start of prenatal care, lower number of prenatal
 visits, and lower body mass index before pregnancy were associated with
 short intervals between pregnancies. Conversely, women with a long
 interpregnancy interval were more likely to be older, with greater body
 mass index before pregnancy, and with a history of chronic hypertension.
 Start of prenatal care and number of prenatal visits correlated with
 interpregnancy interval: the shorter the interval, the later care started
 and the lower the number of prenatal visits. There were no obvious
 differences among the interpregnancy interval groups with regard to number
 of previous deliveries, mother's education, marital status, and cigarette
 smoking during pregnancy.
 
 
 Women with short interpregnancy intervals had the highest rates of third
 trimester bleeding, premature rupture of membranes, puerperal endometritis,
 anaemia, and maternal death (table 2). There were 220 maternal deaths in
 the study population The rates of pre-eclampsia, eclampsia, and gestational
 diabetes mellitus were highest among women with intervals longer than
 59 months. A slight increase in the rates of third trimester bleeding and
 maternal death was also seen in women with this interpregnancy interval.
 
 Table 3 shows the results of multiple logistic regression analysis of the
 relation of interpregnancy intervals to adverse maternal outcomes. Compared
 with mothers with interpregnancy intervals of 18 to 23 months, mothers with
 intervals shorter than 6 months had about a 70% increased risk of third
 trimester bleeding and premature rupture of membranes and a 30% increased
 risk of anaemia and puerperal endometritis. Moreover, a short interval
 between pregnancies was associated with a significantly greater risk of
 maternal death (adjusted odds ratio 2.54; 95% confidence interval 1.22 to
 5.38). When interpregnancy intervals were dichotomised to shorter than
 6 months versus 6 months or more, women with short intervals between
 pregnancies were significantly more likely to die than women conceiving at
 or after 6 months (2.04; 1.13 to 3.78). On the other hand, women with
 interpregnancy intervals of 60 months or more were 1.8 times more likely
 than women with intervals of 18 to 23 months to develop pre-eclampsia and
 eclampsia. We found no significant differences in the effect of
 interpregnancy interval on gestational diabetes mellitus, and no relation
 between the interval and the risk of postpartum haemorrhage.
 
 Our results indicate that women with short intervals (<6 months) between
 pregnancies are at increased risk of maternal death, third trimester
 bleeding, premature rupture of membranes, puerperal endometritis, and
 anaemia. Likewise, long intervals (59 months) were associated with higher
 risks of pre-eclampsia and eclampsia. Our findings are supported by our
 large sample size, which confers sufficient power to evaluate the relation
 between interpregnancy interval and adverse maternal outcomes and by our
 ability to control for the influence of many possible confounding factors.
 
 
 Few studies have examined the effect of interpregnancy interval on maternal
 outcomes. An earlier study from the United States did not find any effect
 of interpregnancy interval on maternal anaemia, puerperal fever, postpartum
 haemorrhage, and maternal mortality, although the number of maternal deaths
 16 was small.6 An increased risk of maternal mortality among Hindu women
 with intervals between pregnancies of less than 24 months compared with
 women with interpregnancy intervals of 24 or more months (relative risk
 2.5; 95% confidence interval 1.5 to 4.3) has been reported in a
 case-control study of 252 maternal deaths matched to 252 survivors by age,
 parity, and booking status.7 As a strong association between maternal death
 and both age and parity was also reported, however, the results of this
 study are difficult to interpret. A recent nested case-control study from
 Bangladesh evaluated risk factors for 390 maternal deaths.9 It found that
 interpregnancy intervals shorter than 9 months did not increase the risk of
 maternal death (adjusted odds ratio 1.29; 95% confidence interval 0.77 to
 2.14) compared with interpregnancy intervals of 15 to 26 months, after
 adjustment for maternal age, area of residence, maternal education,
 religion, and year of birth.9 None the less, women dying within 90 days
 after the end of pregnancy and with external causes of death such as
 induced abortion or suicide were included in the study, which may have
 hidden the existence of an association. In addition, gestational age was
 unknown for 44% of pregnancies, thereby biasing calculation of
 interpregnancy interval.
 
 
 Short interpregnancy intervals and adverse maternal outcomes
 Our finding of higher rates of anaemia among women with short
 interpregnancy intervals agrees with findings of previous studies. 8 14
 With regard to third trimester bleeding a recent population based study
 found a greater risk of uteroplacental bleeding disorders among young
 multiparous women.15 The authors attributed it to a higher incidence of
 short intervals between pregnancies in these women. Our results confirmed
 such an association.
 
 
 The reasons for the association between a short interval between
 pregnancies and adverse maternal outcomes are unclear. Most of our findings
 might be explained by the maternal depletion hypothesis, which suggests
 that short intervals do not allow to the mother to recover from the
 physiological stresses imposed by the previous pregnancy.16-18 This results
 in depletion of maternal nutrient stores and anaemia, which have been found
 to play a part in the pathogenesis of premature rupture of membranes and
 puerperal endometritis. 19 20 With regard to the increased risk of third
 trimester bleeding, we postulate that a short interval between pregnancies
 might interfere in normal processes of remodelling of endometrial blood
 vessels after delivery, with subsequent uteroplacental underperfusion,21
 thereby increasing the likelihood for placental abruption and placenta
 praevia. All the previously mentioned conditions may contribute to the
 increased risk of maternal death among women with short interpregnancy
 intervals found in our study. Other alternative explanations for the
 relation between short interpregnancy intervals and adverse maternal
 outcomes might be postpartum stress levels, socioeconomic factors other
 than marital status and education, unstable lifestyles, occupation,
 community variables (for example, crime, drug misuse, housing), failure to
 use healthcare services or inadequate use of such services, and other
 behavioural or psychological determinants.
 
 
 Long interpregnancy intervals and adverse maternal outcomes
 Results from our study corroborate the finding from an earlier report that
 showed that women with long intervals between pregnancies are at increased
 risk of pre-eclampsia. Eastman reported that compared with mothers with
 interpregnancy intervals of 12 to 23 months mothers with intervals longer
 than 48 months had a significantly greater risk of toxaemia (relative risk
 1.3; 95% confidence interval 1.1 to 1.5).6 Interestingly, the rate of
 pre-eclampsia among nulliparous women recorded in our database (n=325 146)
 was similar to that of parous women who conceived five or more years after
 a previous birth (6.5% versus 6.6%, respectively). It would seem that
 parous women with long interpregnancy intervals behave as nulliparous women
 with regard to the risk of pre-eclampsia as if the "protective" effect for
 pre-eclampsia acquired by a woman through a previous birth is lost after a
 long interval. Certain variables that may confound or modify the relations
 between interpregnancy interval and pre-eclampsia, however, such as change
 in paternity,22 were not available to us for analysis. Regardless of what
 causes this association, women who become pregnant a long time after the
 previous pregnancy are at higher risk of pre-eclampsia and eclampsia and
 need to be carefully monitored during antenatal care. On the other hand,
 after adjustment for confounders, the effect of long interpregnancy
 intervals on gestational diabetes mellitus disappeared. Thus, the increased
 rate of gestational diabetes mellitus associated with intervals greater
 than 59 months could be mediated through older maternal age and higher body
 mass index before pregnancy.
 
 
 Methodological considerations
 Several limitations and potential biases of this study must be considered.
 Firstly, socioeconomic factors are potential confounders for the relation
 between interpregnancy interval and adverse maternal outcomes. In the
 present study, we accounted for only two of these factors (maternal
 education and cohabitation of parents), but we were unable to evaluate the
 relation to other socioeconomic factors such as family income and race
 because these data were not available from the database. Secondly, our
 study was not population based. Rather, it was based at several different
 hospitals spread across Latin American and the Caribbean. In general, less
 than 2% of all Latin American and Caribbean births are represented by our
 database. It is unlikely, however, that the effect of interpregnancy
 interval on adverse maternal outcomes had been confounded by this matter as
 the results were similar among the countries considered in our study.
 Thirdly, the accuracy of specific diagnoses registered on this large
 database has not been extensively investigated and only local medical
 records have been verified.23 As such, data from the database are limited
 to a certain extent. Fourthly, despite adjustment for several variables,
 there is still potential for confounding by other unknown factors. Fifthly,
 inaccuracy of gestational age estimated from the date of last menstrual
 period is a well recognised problem in epidemiological research on
 interpregnancy intervals. When we replicated the entire analyses using
 gestational age estimated from physical and neurological assessments of the
 newborn instead of that based on last menstrual period, the results were
 essentially unchanged. Finally, it should be emphasised that our study was
 carried out in developing countries and its findings may therefore not be
 applicable to other populations.
 
 
 The risks for maternal perinatal morbidity and mortality associated with
 short interpregnancy intervals underscore the importance of birth spacing
 by using the available methods of family planning, particularly after a
 birth, to promote safe motherhood and achieve better pregnancy outcomes. In
 addition, women should be advised of the potential harm to them and their
 infants of short and long intervals between pregnancies.
 
 What is already known on this topic?


 Both short and long intervals between pregnancies are associated with
 adverse perinatal outcomes


 Conflicting data exist on the impact of interpregnancy interval on  maternal morbidity and mortality


 What does this study add?


 Women with interpregnancy intervals shorter than 6 months are at  increased risk of maternal death, third trimester bleeding, premature  rupture of membranes, puerperal endometritis, and anaemia


 Women with interpregnancy intervals longer than 59 months are at  increased risk of pre-eclampsia and eclampsia


 As the research was carried out in developing countries the results may  not apply to other populations

 We thank Mr Roberto Porro and Dr Felipe Santana for the preparation of the
 database. We also thank health workers and health related workers in many
 settings of the Latin American and Caribbean region for their efforts to
 collect and send Perinatal Information System data to the Latin American
 Centre for Perinatology and Human Development.
 
 
 Contributors: AC-A originated and designed the study, analysed the data,
 and was mainly responsible for writing the paper; he will act as guarantor
 of the paper. JMB participated in the discussion of the study hypothesis
 and study design, contributed to the analyses, and helped to write the
 paper.
 
 
 
 Funding: Division of Health Promotion and Protection, Pan American Health  Organisation.
 
 
 Competing interests: None declared.
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 (Accepted 11 September 2000)
 © BMJ 2000 (Embedded image moved to file: pic30498.gif)
 

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