Factors associated with changes in leisure time physical activity during early pregnancy

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CLINICAL ARTICLE

Factors associated with changes in leisure time physical activity during early pregnancy

Carmen Amezcua-Prieto

^a,b,

⁎ , Rocío Olmedo-Requena

^a,b

, Eladio Jiménez-Mejías

^a,b

, Juan Mozas-Moreno

^c

, Pablo Lardelli-Claret

^a,b

, José J. Jiménez-Moleón

^a,b

aDepartment of Preventive Medicine and Public Health, University of Granada, Granada, Spain

bBiomedical Research Centre Network for Epidemiology and Public Health (CIBERESP), Granada, Spain

cObstetrics and Gynecology Service, Virgen de las Nieves University Hospital, Granada, Spain

a b s t r a c t a r t i c l e i n f o

Article history:

Received 3 July 2012

Received in revised form 17 November 2012 Accepted 24 January 2013

Keywords:

Early pregnancy

Leisure time physical activity Pre-pregnancy lifestyle changes Recommendations

Objective:To identify key factors involved in modifying leisure time physical activity (LTPA) during early pregnancy.Methods:A prospective study was conducted of 1175 pregnant women who attended a scheduled visit at Virgen de las Nieves University Hospital, Granada, Spain, at 20–22 weeks of pregnancy. The Paffenbarger Physical Activity Questionnaire was used to collect data regarding participation in any LTPA or physical activity performed according to society recommendations during early pregnancy and in the year before pregnancy. A polytomous regression model was used to identify factors associated with LTPA.

Results:Approximately 20.0% of the women did not engage in any LTPA, and 68.0% did not achieve the recommendations for exercise, either before or during pregnancy. Desirable changes related to performing any LTPA or the society recommendations for LTPA during pregnancy were associated with university level of education (aOR, 3.64 [95% CI, 1.54–8.56] and aOR, 1.75 [95% CI, 0.67–4.57], respectively) and smoking cessation at pregnancy (aOR, 2.05 [95% CI, 0.97–4.35] and aOR, 4.83 [95% CI, 1.31–17.83], respectively).

Conclusion:Few women achieved the minimum recommendations for exercise before or during pregnancy.

Nevertheless, adoption of healthy lifestyle choices during pregnancy seemed to promote other healthy habits, such as participation in LTPA.

1. Introduction

General agreement exists when recommending physical activity during pregnancy[1–3]. The American Congress of Obstetricians and Gynecologists (ACOG) and the Royal College of Obstetricians and Gynaecologists (RCOG) recommend that healthy pregnant women should undertake moderate physical activity for at least 30 minutes every day (or nearly every day)[1,2]. Numerous studies have demon- strated that walking is the most popular type of leisure time physical activity (LTPA) that pregnant women perform[4–6].

Participating in physical activity on a regular basis is fundamental for health and decreases the risk of various conditions, including hypertension, type 2 diabetes mellitus, obesity, and diseases related to the cardiovascular system[7]. Among pregnant women, the beneﬁts of exercise include reduced risk of gestational diabetes mellitus, reduced weight gain, reduced difﬁculties during labor, and improved emotional well-being[8,9]. In addition, performing exercises during pregnancy has advantages for the fetus and the newborn[10–12].

Despite the potential beneﬁts of undertaking physical activity during pregnancy, some studies have reported a low prevalence of

compliance with the recommendations. For example, a prevalence of approximately 20% has been recorded in the USA, Spain, and Ireland [4,5,13], while the prevalence in Portugal is 16%[14]. Furthermore, some studies have suggested that a decrease in the duration and intensity of LTPA may occur during pregnancy in relation to the previous non-pregnant year[15]. It would, therefore, be helpful to identify the main factors associated with decreasing LTPA in order to develop appropriate intervention strategies. Nevertheless, few studies have explored the factors potentially associated with undesirable changes in physical activity during pregnancy, and the results are not consis- tent, possibly owing to the methodology used to assess the level of physical activity, the time of measurement, or characteristics of the sample population[16].

The aim of the present study was to determine the key factors associated with decreasing or increasing LTPA during early pregnancy versus the year before pregnancy.

2. Materials and methods

A prospective study of 1175 healthy pregnant women was conducted. The eligible population comprised all Spanish women attending a scheduled visit between 20 and 22 weeks of pregnancy at the Virgen de las Nieves University Hospital, Granada, Spain, between June 1, 2004, and October 31, 2007. Approval was obtained from the Virgen de las Nieves University Hospital Ethics Committee International Journal of Gynecology and Obstetrics xxx (2013) xxx–xxx

⁎ Corresponding author at: Departamento de Medicina Preventiva y Salud Pública, Universidad de Granada, Avenida de Madrid 11, 18071 Granada, Spain. Tel.: + 34 958 241 000x20287; fax: +34 958 246 118.

E-mail address:[email protected](C. Amezcua-Prieto).

http://dx.doi.org/10.1016/j.ijgo.2012.11.021

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International Journal of Gynecology and Obstetrics

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / i j g o

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and the University of Granada Ethics Committee. All eligible women signed a form of agreement before participation[5].

Inclusion criteria were coverage by the Andalusian Programme of Infant–Maternal Health (a free universal healthcare program for all pregnant women living in Andalusia that includes a scheduled visit at 20–22 weeks of pregnancy, during which abdominal ultrasonogra- phy is performed); singleton pregnancy; no pregnancy-related com- plications requiring bed rest; and residence in the catchment area of the study center. The Virgen de las Nieves University Hospital serves as reference facility for the north of Granada; this region includes approximately 400 000 inhabitants, with approximately 4000 births each year[17].

Study data were collected through a structured face-to-face survey, taken just before the ultrasound examination and performed by 2 interviewers who had already been trained in this issue. Along with sociodemographic, obstetric, and lifestyle variables, information about LTPA in the year before pregnancy and during the first 20–22 weeks of the current pregnancy was obtained using the Paffenbarger Physical Activity Questionnaire[18]. Information recorded with this questionnaire included type of LTPA, frequency (number of days per week), and duration (minutes per session). Each type of LTPA was assigned a pre-specified metabolic equivalent of task (MET), a measure of energy expenditure in calories per hour, according to the updatedCompendium of Physical Activities [19]. Individual MET scores were calculated as follows: MET minutes/week= (MET–level) x (minutes/day) x (days/week). The accuracy and validity of the questionnaire were analyzed in a previous study of 50 pregnant women not included in the present study[20]. The accuracy of the questionnaire was excellent, with a pooled Spearman r correlation coefficient (rs) of 0.90. A Caltrac accelerometer was used to validate the present study.

The correlation between the questionnaire and the accelerometer was similar to the correlation reported previously[21].

A systematic sample of 1222 women was initially recruited, equivalent to 1 in 5 of the eligible population. Nineteen women (1.6%) did not complete the interview, 15 women (1.2%) had incomplete data, and 13 women (1.1%) chose not to participate in the present study.

Theﬁnal sample size was therefore 1175 (96.1% of the initial sample).

This sample size was originally designed to meet the requirements of a population-based case–control study, serving as the population control group. However, the distribution according to LTPA performance before and during pregnancy provided a power of 93% to detect an odds ratio (OR) equal to or higher than 2, enabling measurement of the strength of associations between unfavorable changes in LTPA and any related factors with a prevalence of 20% in the control group (i.e. women who did not perform any LTPA before or during pregnancy) and anαvalue of 0.05.

The women were classiﬁed into 4 groups deﬁned by the variable

“ANY-LTPA:” 1-1 (some form of LTPA performed both before and during pregnancy); 0-1 (LTPA performed during pregnancy only); 1-0 (LTPA performed before pregnancy only); and 0-0 (no LTPA performed either before or during pregnancy). Furthermore, considering all recorded information about LTPA type, frequency, and duration, a second dichotomous variable (“RECOMMENDED-LTPA”) was created.

This variable was deﬁned as either meeting or not meeting the Centers for Disease Control and Prevention and the American College of Sports Medicine (CDC/ACSM) guidelines on physical activity and public health. The Committee on Exercise and Cardiac Rehabilitation of the American Heart Association supported these guidelines, which recommend moderate-to-vigorous LTPA requiring a minimum of 450 MET minutes/week[22]. These guidelines are equivalent to the ACOG and RCOG recommendations for pregnant women[1,2]. Women were clas- siﬁed into 4 groups according to RECOMMENDED-LTPA: 1-1 (women above the recommended limit both before and during pregnancy);

0-1 (women above the limit only during pregnancy); 1-0 (women above the limit only before pregnancy); and 0-0 (women below the limit both before and during pregnancy).

Data were analyzed using Stata version 11.0 (StataCorp, College Station, TX, USA). Polytomous regression models were constructed to evaluate the relationship between a set of independent variables and the status of participants according to ANY-LTPA and RECOMMENDED- LTPA. In both models, the reference category for the dependent variable was 0-0. Independent variables included age, body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters), educational level, smoking status, parity, previous spontaneous abortion, energy intake, and MET of LTPA before pregnancy. A similarity ratio test was used to examine the existence of interactions between pairs of independent variables. APvalue below 0.05 was considered statistically signiﬁcant.

3. Results

Supplementary Material S1shows the main sociodemographic fea- tures of the study group. At interview, the mean maternal age was 29.8 ± 5.14 years and the mean gestational age was 21 ± 3.7 weeks.

Prior to pregnancy, 36.5% of the women smoked; however, approximately 50.0% ceased smoking during the early months of pregnancy.

Most women (68.6%) performed some LTPA before and during pregnancy (category 1-1), whereas 19.4% did not perform any LTPA before or during pregnancy (category 0-0). The frequency of women who showed undesirable changes—from some LTPA before pregnancy to no LTPA during pregnancy—was 4.7% (category 1-0). Conversely, 7.3% of the women showed a positive change in LTPA during pregnancy (category 0-1).

The polytomous regression analysis for the ANY-LTPA variable is shown inTable 1. Category 0-0 was used as the reference population.

Category 1-1 was positively associated university level of education;

the adjusted OR (aOR) was 1.31 (95% conﬁdence interval [CI], 1.22–3.73). Cessation of tobacco smoking before or during pregnancy was also associated with category 1-1; the aOR was 2.06 (95% CI, 1.19–3.58) before pregnancy and 2.14 (95% CI, 1.22–3.73) during pregnancy. The frequency of undesirable changes (category 1-0) was directly related to social class II (aOR, 3.72 [95% CI, 1.00–13.90]) and inversely related to a monthly family income below €3000 (aOR, 0.10 [95% CI, 0.02–0.47]) and previous deliveries (aOR, 0.37 [95% CI, 0.17–0.80]). Finally, positive changes (category 0-1) were associated with university education (aOR, 3.64 [95% CI, 1.54–8.56]) and tobacco cessation at the onset of pregnancy (aOR, 2.05 [95% CI, 0.97–4.35]).

The polytomous regression analysis for the RECOMMENDED-LTPA variable is shown inTable 2. Only 14.9% of the women complied with recommendations before and during pregnancy; most of the women (68.0%) were in group 0-0 (i.e. not achieving minimum recommendations regarding LTPA either before or during pregnancy). In the adjusted model, factors positively associated with group 1-1 were non-smoking (aOR, 2.00 [95% CI, 1.00–3.98]) and age 30–35 years (aOR, 2.55 [95% CI, 1.07–6.06]). An inverse correlation was found for previous deliveries (aOR, 0.55 [95% CI, 0.33–0.92]).

No variable was clearly associated with undesirable changes in LTPA (category 1-0). However, positive changes (group 0-1) were directly related to tobacco cessation before (aOR, 5.66 [95% CI, 1.57–20.30]) or during (aOR, 4.83 [95% CI, 1.31–17.83]) pregnancy and to university education (aOR, 1.75 [95% CI, 0.67–4.57]), but inversely related to low monthly family incomes (aOR, 0.33 [95% CI, 0.12–0.90]). All interactions tested in both models were non-signiﬁcant.

4. Discussion

Although the practice of some form of LTPA was frequent before and during pregnancy, theﬁndings of the present study suggest that few women met the recommendations proposed by CDC/ACSM and the American Heart Association (before pregnancy) or ACOG and RCOG (during pregnancy)—just 27.5% before pregnancy and 19.4%

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during pregnancy. CDC/ACSM and the American Heart Association recommendations are equivalent to ACOG and RCOG recommendations for healthy pregnant women. Furthermore, a substantial pro- portion decreased their LTPA during pregnancy; in all, 45.8% of the women who met the recommendations in the year before pregnancy did not comply during pregnancy.

Regular physical activity is known to provide important beneﬁts for the mother and fetus. However, previous studies on physical activity in pregnancy concluded that a progressive decrease occurs in the intensity and duration of exercise throughout pregnancy[6,23].

Factors related to this trend should be explored given that only a small number of women perform the recommended 30 minutes or more of moderate physical activity on most or all days throughout pregnancy[4,5,24].

Few studies have addressed this issue; however, some report that pregnant women reduce their LTPA because they feel very tired, espe- cially at the beginning of their pregnancy[25]. In a study of 1737 pregnant women, Fell et al.[16]found that the main characteristics of women who discontinued exercise or sports during pregnancy were obesity, age below 35 years, more than 1 child, and low educational level. Nevertheless, these researchers did not analyze the characteristics of those women who showed a positive change in LTPA during pregnancy. The aim of the present study was to overcome this limitation and shed light on factors related to positive or negative changes in LTPA.

The patterns of associations detected in the present study partially agree with previous observations [16,23]. Overall, maintaining or acquiring the practice of LTPA was associated with high educational level and an age of 30–35 years. However, the main factor associated with LTPA during pregnancy was tobacco cessation. This feature cor- related strongly with maintaining or increasing any pre-pregnancy

LTPA, as well as with increasing LTPA over the minimum recommendations during pregnancy. Indeed, the strength of this association suggests that pregnant women maintain or adopt healthy lifestyles perceived to be of beneﬁt to the fetus[26].

Counseling on physical activity is usually a neglected area in maternal health promotion. Promotion of LTPA along with the advice usually given on other unhealthy lifestyles, such as alcohol consumption or tobacco smoking, is clearly important when attending pregnant women. Therefore, family doctors, midwives, and prenatal healthcare providers might include LTPA counseling during pregnancy and later, in addition to the rest of their daily activities: child and adult care giving, and indoor/outdoor household and occupational activities.

In order to facilitate the performance of LTPA and to reduce the negative consequences of lack of exercise, pregnant women should be encouraged to participate in activities that can be easily integrated into their daily routine. Such activities might include walking from home to work, walking the dog, putting out the garbage, taking or collecting children from school on foot, using stairs instead of lifts, or increasing the frequency of walking to the shops (so as to carry less weight on the return journey). Some speciﬁc additional measures might include offering an exercise chart throughout pregnancy in preparing for delivery.

Several methodologic considerations should be taken into account when interpreting the results of the present study. First, the selection procedure and the low rate of non-response support the representative nature of the study population versus the reference population (all healthy pregnant women from a deﬁned geographic area). The fact that the study population was enrolled at a single hospital could result in possible referral bias; however, every pregnant woman comprising the study sample can be taken as representative of a healthy population of pregnant women. The Virgen de las Nieves Table 1

Factors associated with changes in the performance of any leisure time physical activity before and during pregnancy.^a 0-0: Reference category^b

(n = 228; 19.4%)

1-1: No changes^b (n = 806; 68.6%)

1-0: Undesired changes^b (n = 55; 4.7%)

0-1: Desired changes^b (n = 86; 7.3%)

Variable Category cOR 95% CI aOR^c 95% CI cOR CI 95% aOR^c 95% CI cOR 95% CI aOR^c 95% CI

Age, y b25 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

25–29 1.58 1.03–2.45 1.23 0.73–2.10 1.34 0.55–3.26 1.01 0.38–2.67 1.33 0.67–2.67 1.51 0.72–3.18 30–35 1.96 1.29–3.00 1.24 0.70–2.20 1.36 0.57–3.25 0.97 0.34–2.75 1.02 0.50–2.07 1.26 0.54–2.94

≥35 2.24 1.34–3.68 1.43 0.74–2.78 1.60 0.59–4.36 1.25 0.40–4.05 0.85 0.35–2.07 1.04 0.37–2.90

BMI b25 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

25–30 1.04 0.73–1.50 1.31 0.86–2.02 0.94 0.45–1.98 1.17 0.53–2.58 1.21 0.67–2.17 1.19 0.65–2.20

≥30 0.92 0.56–1.51 1.14 0.63–2.04 1.42 0.59–3.43 1.77 0.67–4.69 0.91 0.39–2.16 0.87 0.35–2.15 Educational level Primary 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference Secondary 1.53 1.08–2.18 1.23 0.78–1.96 1.93 0.97–3.87 1.52 0.68–3.43 0.94 0.50–0.96 1.11 0.54–2.26 University 2.13 1.47–3.09 1.31 1.22–3.73 1.81 0.86–3.81 1.01 0.35–2.85 1.72 0.96–3.12 3.64 1.54–8.56 Social class^d I 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference II 0.67 0.35–1.26 1.06 0.50–2.25 2.01 0.60–6.73 3.72 1.00–13.90 1.03 0.34–3.14 1.03 0.32–3.29 III 0.54 0.32–0.92 0.84 0.44–1.64 1.15 0.38–3.45 1.60 0.45–5.73 1.00 0.39–2.52 1.19 0.43–3.30 IV–V 0.48 0.29–0.78 1.28 0.63–2.60 0.82 0.28–2.40 1.67 0.43–6.55 1.07 0.44–2.58 1.66 0.56–4.93 Monthly family income,€ >3000 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 2000–3000 0.49 0.20–1.21 0.49 0.18–1.37 0.15 0.38–0.60 0.10 0.02–0.47 1.70 0.19–15.37 1.71 0.18–15.98 1000–2000 0.37 0.15–0.87 0.42 0.15–1.17 0.25 0.75–0.82 0.20 0.05–0.81 2.32 0.27–19.73 3.29 0.36–29.92 b1000 0.28 0.11–0.70 0.42 0.14–1.26 0.20 0.53–0.78 0.22 0.04–1.10 2.86 0.32–25.32 4.95 0.51–48.21 Tobacco use Smoked during pregnancy 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

Cessation at pregnancy 1.88 1.17–3.03 2.14 1.22–3.73 1.89 0.73–4.90 2.07 0.76–5.70 1.88 0.92–3.87 2.05 0.97–4.35 Cessation before pregnancy 2.28 1.44–3.61 2.06 1.19–3.58 1.27 0.46–3.50 1.29 0.44–3.79 0.98 0.44–2.19 1.02 0.44–2.33 Never smoked 1.92 1.31–2.81 1.43 0.89–2.28 1.77 0.80–3.93 1.49 0.63–3.55 0.94 0.49–1.80 0.89 0.45–2.33

Parity 0 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

1 0.83 0.61–1.14 0.73 0.48–1.10 0.45 0.22–0.90 0.37 0.17–0.80 0.62 0.36–1.07 0.72 0.39–1.34

≥2 0.79 0.49–1.27 0.70 0.38–1.30 0.66 0.25–1.72 0.54 0.18–1.65 0.61 0.26–1.43 0.68 0.27–1.73 Previous spontaneous abortion 0 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

≥1 0.92 0.64–1.31 0.73 0.47–1.15 0.79 0.37–1.68 0.74 0.32–1.69 0.88 0.47–1.62 1.13 0.58–2.19 Abbreviations: aOR, adjusted odds ratio; BMI, body mass index (calculated as weight in kilograms divided by the square of height in meters); CI, conﬁdence interval; cOR, crude odds ratio; LTPA, leisure time physical activity; MET, metabolic equivalent of task.

aData derived from a prospective series of 1175 Spanish women interviewed at 20–22 weeks of pregnancy.

b 0-0, women in the reference category did not perform any LTPA, either before or during pregnancy; 1-1, women did perform any LTPA before and during pregnancy; 1-0, women did perform any LTPA before but not during pregnancy; 0-1, women did not perform any LTPA before but did during pregnancy.

c Adjusted by all of the factors shown in the table, plus energy intake and the number of MET of LTPA before pregnancy.

d I, upper-middle class; II, middle class; III, lower-middle class; IV, skilled and semiskilled manual workers; V, unskilled manual workers.

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University Hospital is a public maternity hospital catering for approximately 400 000 inhabitants of Granada. All pregnancies monitored by the obstetricians within this unit, as well as pregnancies monitored by external family practitioners and obstetricians, are delivered at Virgen de las Nieves University Hospital. Only an insigniﬁcant bias would be caused by the loss of pregnant women who decided to deliver at a private institution (7%–10% in the northern region of Granada). Conversely, the present study did not consider pregnancies with high obstetric risk, so a referral bias is unlikely to have occurred.

Second, although some recall bias cannot be ruled out, it would be reduced in the present prospective study where the period of time between recruitment and assessment of LTPA was very short, as opposed to studies where information was collected at the end of pregnancy or after delivery[27]. Third, the questionnaire used to collect the LTPA data had been validated in a Spanish adult population [28]and in Spanish pregnant women [20]. Fourth, an element of subjectivity exists in such a survey of physical activity, with possible overestimation by women aware that their LTPA level may not be appropriate, which could make the study group homogenous and interfere with the association of variables. Fifth, regarding external validity, the frequency of women who reported the performance of any LTPA before pregnancy, and the sociodemographic and obstetric characteristics of the study sample, resembled those of previous studies in high-income countries[4,15]. Finally, the study sample was initially designed to investigate the relationship between physical activity and gestational diabetes mellitus, and its size may have hindered analysis of some important factors associated with changes in the level of LTPA before and during pregnancy.

The present study reveals that pregnancy may lead to a decreased frequency and intensity of LTPA. However, it also signals that an

awareness of the potential effects on the fetus of unhealthy habits, such as smoking, could be the key to modifying lifestyle during pregnancy. Understanding the possible reasons behind these behavioral changes is paramount. For this aim, a quantitative method like that used in the present study may not the best choice. Instead, a qualita- tive approach should be used to increase understanding of the factors that underpin decreased LTPA during pregnancy and to aid design of an adequate intervention for improving lifestyles. Hence, if pregnant women were adequately counseled about LTPA and the minimum amount of exercise that provides health beneﬁts for both them and their offspring (and if the reasons for their behavior were known), they might be more successful in making positive changes regarding LTPA. Pregnancy should, therefore, be considered a particularly favorable period for implementing health promotion measures aimed at achieving long-term healthy lifestyle choices among women.

Supplementary data to this article can be found online athttp://

dx.doi.org/10.1016/j.ijgo.2012.11.021.

Acknowledgments

The present study was funded by the Ministry of Health project FIS PI03/1207 and the 2005 excellence project of the Junta de Andalucia (CTS 942), as well as by the Centro de Investigación Biomédica en Red en Epidemiología y Salud Pública (CIBERESP).

Conﬂict of interest

The authors have no conﬂicts of interest.

Table 2

Factors associated with recommended physical activity before and during pregnancy.^a 0-0: Reference category^b

(n = 799; 68.0%)

1-1: No changes^b (n = 175; 14.9%)

1-0: Undesired changes^b (n = 148; 12.6%)

0-1: Desired changes^b (n = 53; 4.5%)

Variable Category cOR 95% CI aOR^c 95% CI cOR 95% CI aOR^c 95% CI cOR 95% CI aOR^c 95% CI

Age, y b25 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

25–29 1.41 0.77–2.61 1.29 0.55–3.03 1.00 0.57–1.77 0.81 0.37–1.77 1.75 0.56–5.47 1.44 0.43–4.84 30–35 2.63 1.48–4.70 2.55 1.07–6.06 1.42 0.83–2.44 1.11 0.50–2.47 3.04 1.03–8.94 2.36 0.70–7.95

≥35 2.11 1.11–4.00 1.59 0.61–4.13 1.37 0.74–2.52 0.86 0.35–2.08 2.97 0.94–9.46 2.31 0.63–8.52

BMI b25 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

25–30 0.75 0.50–1.14 0.96 0.55–1.67 1.16 0.77-1.76 1.39 0.81-2.38 0.44 0.19–1.00 0.50 0.21–1.15

≥30 0.52 0.27–1.00 0.74 0.32–1.74 1.27 0.74–2.19 1.71 0.82–3.56 0.27 0.06–1.16 0.29 0.06–1.27 Educational level Primary 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference Secondary 1.98 1.29–3.04 1.60 0.86–2.96 1.59 1.05–2.40 1.43 0.80–2.56 1.32 0.61–2.88 0.92 0.39–2.20 University 2.80 1.87–4.20 1.75 0.87–3.52 1.12 0.72–1.76 0.63 0.30–1.30 2.87 1.49–5.55 1.75 0.67–4.57 Social class^d I 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference II 0.63 0.35–1.14 1.25 0.53–3.00 0.93 0.50–1.81 1.14 0.50–2.59 0.48 0.17–1.32 0.50 0.19–1.35 III 0.66 0.41–1.06 1.10 0.50–2.36 0.72 0.41–1.25 0.64 0.30–1.37 0.49 0.22–1.05 0.37 0.13–1.01 IV–V 0.36 0.22–0.57 0.88 0.37–2.09 0.57 0.33–0.96 0.66 0.29–1.51 0.37 0.17–0.76 0.68 0.19–2.39 Monthly family income,€ >3000 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 2000–3000 0.99 0.47–2.09 1.47 0.53–4.06 0.87 0.40–1.90 1.06 0.39–2.92 0.37 0.15–0.91 0.46 0.17–1.23 1000–2000 0.68 0.33–1.38 1.47 0.53–4.10 0.64 0.31–1.35 0.79 0.29–2.16 0.19 0.08–0.44 0.33 0.12–0.90 b1000 0.54 0.24–1.21 1.94 0.58–6.49 0.51 0.22–1.20 0.78 0.23–2.56 0.24 0.09–0.66 0.64 0.18–2.25 Tobacco use Smoked during pregnancy 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference Cessation at pregnancy 1.39 0.75–2.58 1.44 0.62–3.31 1.17 0.62–2.19 1.22 0.54–2.75 5.06 1.41–18.10 4.83 1.31–17.83 Cessation before pregnancy 1.98 1.11–3.52 1.74 0.80–3.80 1.63 0.91–2.93 1.73 0.82–3.69 6.73 1.94–23.30 5.66 1.57–20.30 Never smoked 2.37 1.47–3.95 2.00 1.00–3.98 1.77 1.06–2.96 1.63 0.83–3.18 3.43 1.00–11.76 2.49 0.70–8.85

Parity 0 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

1 0.70 0.49–1.00 0.55 0.33–0.92 0.83 0.56–1.22 0.62 0.37–1.04 0.71 0.39–1.30 0.61 0.31–1.20

≥2 0.59 0.32–1.08 0.41 0.17–0.96 1.13 0.66–1.94 0.70 0.32–1.55 0.41 0.12–1.37 0.33 0.09–1.20 Previous spontaneous abortion 0 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference 1.00 Reference

≥1 0.91 0.60–1.38 0.92 0.52–1.61 1.17 0.77–1.78 1.08 0.62–1.86 1.27 0.67–2.44 1.56 0.77–3.16 Abbreviations: aOR, adjusted odds ratio; BMI, body mass index (calculated as weight in kilograms divided by the square of height in meters); CI, conﬁdence interval; cOR, crude odds ratio; LTPA, leisure time physical activity; MET, metabolic equivalent of task.

aData derived from a prospective series of 1175 Spanish women interviewed at 20–22 weeks of pregnancy.

b 0-0, women in the reference category did not perform any recommended physical activity, either before or during pregnancy; 1-1, women did perform any recommended physical activity before and during pregnancy; 1-0, women did perform any recommended physical activity before but not during pregnancy; 0-1, women did not perform any recommended physical activity before but did during pregnancy.

c Adjusted by all of the factors shown in the table, plus energy intake and number of MET of LTPA before pregnancy.

d I, upper-middle class; II, middle class; III, lower-middle class; IV, skilled and semiskilled manual workers; V, unskilled manual workers.

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