LOGO National Research Institute for Family Planning Preconception Blood Pressure and Risk of Preterm delivery in Chinese reproductive age women Yang Y,

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National Research Institute for Family Planning

Preconception Blood Pressure and Risk of Preterm delivery in Chinese reproductive age women

Yang Y, Wang YY, Ma LG, Peng ZQ, Ma X.

Aug 18th, 2014 Beijing

2nd International Conference on Epidemiology & Evolutionary Genetics

Presenter: Ying Yang

www.themegallery.com

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Outline

1

Methods2

Results3

Conclusion4

Background and objective


Background

Preterm delivery (PTD) is an important adverse pregnancy outcome in pregnant women, which threaten maternal and child health1.

The report of WHO in 2012 showed that around 1 million children die each year due to complications of preterm birth. Many survivors face a lifetime of disability, including learning disabilities and visual and hearing problems.

1. Blencowe H, et al. National, regional and worldwide estimates of preterm birth. The Lancet, June 2012. 9;379(9832):2162-72.


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Background An estimated 15 million babies are born too soon

every year. In China, there are 11.7 million preterm births, second to India.The 10 countries with the greatest number of preterm births:

Countries No. of Preterm Births

India 3,519,100

China 1,172,300

Nigeria 773,600

Pakistan 748,100

Indonesia 675,700

USA 517,400

Bangladesh 424,100

Philippines 348,900

Congo 341,400

Brazil 279,300


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Background

Pre-pregnancy period

Preterm DeliveryRisk factors

Gestation periodNutrition situation

Pregnancy Complications

SmokingAlcohol consumption

Multiple gestation

environmental stimulus

Uncertain

Background

Effective PCC interventions could be an opportunity to improve pregnancy outcomes.

Weight

Blood glucose

Blood pressure

Family history

Life style


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Objective

To examine the association between preconception blood pressure (BP) and the risk of PTD in a historical cohort of reproductive age women in Chinese rural population.


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Methods Study design

A historical cohort study of reproductive age women in Chinese

rural population.

Study population

Rural reproductive age women who participated in National

Free Pre-pregnancy Checkups (NFPC) in 2010-2012 and had

live-born babies before Oct 2013 were recruited in the present

study.

Participants suffered from adverse pregnancy outcomes such

as fetal death, still birth and abortion were excluded.


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Methods National Free Pre-pregnancy Checkups (NFPC)

NFPC is a population-based health survey of reproductive-age couples, which is supported by National Health and Family Planning Commission since 2010, and have been comprehensively implemented in all provinces in China.


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Objects• Couples who prepare for pregnancy

Pre-pregnancy medical examination record • Information on disease/family/obstetric history, life styles

and socioeconomic background were carefully collected through face-to-face interview by qualified nurses.

• The physical and laboratory examination were also carried out at the same time, including height, weight, blood pressure, fasting glucose, thyroid-stimulating hormone, TORCH, HBV test, Gynecological B-ultrasonography, and so on.


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Follow-up information• A comprehensive evaluation for reproductive risk of

participants were provided after the medical examination.

• After that, two follow-up surveys were carried out by trained staffs. One was in the first trimester during pregnancy, and the other was after delivery.

• The information of LMP and FA supplement usage in the first trimester, pregnancy outcomes as well as the newborn information were collected through telephone or face to face interview.

Methods

NFPC participants Jan 2010 to Dec 2012

Participants who are failure to get pregnant,

suffered from fetal death, still birth abortion,

Lost to follow-up

388,708 women have live-birth before Oct 2013

Participants lack of preconception blood

pressure records

377,844 women have live-birth before Oct 2013

Study population


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Methods Baseline data

In the present study, preconception blood pressure, height,

weight, history of pregnancy and diseases, life style, fasting

glucose level and other variables were obtained from the NFPC

family archives in 2010-2012.

Follow-up data collection

Follow-up survey period was from June 2010 to Oct 2013.

Preterm delivery (PTD) which is defined as babies born alive

within 28 to 37 weeks of pregnancy are completed, were the

end point event.


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Methods Statistical analysis

Study participants were grouped into several categories

according to preconception systolic BP (SBP) or diastolic

BP (DBP) separately.

To compare the strength of the association between

preconception SBP, DBP and PTD, the relative risks for

each cut-point of SBP and DBP were calculated,

separately, using the lowest BP level group as the

reference categories.

Multivariate Logistic regression models were used to

estimate the relative risk (RR) on PTD.


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ResultsTable 1. Baseline characteristics of study participants

Characteristics Normotension Hypertension P-value

N(%) 368855(97.6) 8989(2.4) -

age[year, mean(SD)] 27.7(4.2) 29.3(4.9) <0.001

High school education(%) 29.6 24.5 <0.001

smoking (%) 0.3 0.3 0.989

Alcohol consumption (%) 3.0 3.1 0.557

BMI[kg/m2, mean (SD)] 21.0(2.6) 22.8(3.8) <0.001

SBP [mmHg, mean (SD)] 108.6(9.6) 129.1(15.0) <0.001

DBP [mmHg, mean (SD)] 71.3(6.9) 90.9(7.5) <0.001

Glucose [mmol/L, mean (SD)] 4.9(1.6) 5.0(1.2) <0.001

Thyroid dysfuction(%) 13.8 17.7 <0.001

History of adverse pregnancy outcomes(%) 17.3 24.1 <0.001

Northern residents (%) 40.1 51.1 <0.001


Results

End point events

Until Oct 2013, 377,844 live births were included in the

historical cohort, and a total of 3579 PTD events were

documented.

Data analysis strategy

In consideration of that multiple gestation may

significantly increased the PTD risk, multiple gestation

women were excluded from the analysis.

Finally, 370,784 participants who have singleton live

births were included in the statistic analysis.


Results

Table 2. Incidence and RR of PTD by preconception SBP level

SBP

(mmHg)

PTD incidence

（%）RRa (95%CI) P-valuea RRb (95%CI) P-valueb

<120 0.87 1.00 - 1.00 -

120-139 1.03 1.14(1.05-1.24) 0.001 1.20(1.10-1.32) <0.001

140-159 1.96 1.97(1.43-2.73) <0.001 2.14(1.52-3.13) <0.001

>=160 2.63 2.41(1.14-5.10) 0.022 3.13(1.48-6.66) 0.003

a adjusted for age.b adjusted for age, BMI, smoking, alcohol consumption, diabetes, thyroid

dysfunction, history of adverse pregnancy outcome, northern residents and high school education.


Results

Table 3. Incidence and RR of PTD by preconception DBP level

DBP

(mmHg)

PTD incidence

（%）RRa (95%CI) P-valuea RRb (95%CI) P-valueb

<80 0.81 1.00 - 1.00 -

80-89 1.01 1.26(1.16-1.36) <0.001 1.30(1.18-1.42) <0.001

90-99 1.40 1.67(1.35-2.06) <0.001 1.72(1.36-2.17) <0.001

>=100 2.05 2.31(1.44-3.69) <0.001 2.52(1.53-4.17) <0.001

a adjusted for age.b adjusted for age, BMI, smoking, alcohol consumption, diabetes, thyroid

dysfunction, history of adverse pregnancy outcome, northern residents and high school education.

Results

<120 120-139 140-159 >=1600.00

1.00

2.00

3.00

4.00

0.00

1.00

2.00

3.00

4.00

Preconception SBP level and PTD risk

PTD incidence adjusted RRa adjusted RRb

SBP level

adju

sted

RR

PTD

incid

ence

(%)

<80 80-89 90-99 >=1000.00

1.00

2.00

3.00

0.00

1.00

2.00

3.00

Preconception DBP level and PTD risk

PTD incidence adjusted RRa adjusted RRb

DBP level

adju

sted

RR

PTD

incid

ence

(%)

There is a strong linear and independent relationship

between BP levels and the risk of PTD in Chinese

reproductive age women.


Discussion

Preconception BP elevated

Preterm DeliveryRisk

Gestation periodPregnancy induce

hypertension syndrome(PIH)

Gestational hypertension

Fetal growth restriction

Increase


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Conclusion

The risk of PTD was significantly associated with

maternal preconception blood pressure.

The higher the SBP or DBP level, the higher the

relative risk of PTD incidence in Chinese

reproductive age women.

Preconception health care especially preconception

BP measurements and specific hypertension

intervention are important and necessary towards

women who prepares for pregnancy.


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Acknowledgement

Thanks to all the staffs of National Research Institute for

Family Planning.

Thanks to the staffs of National Free Pre-pregnancy Checkups.

Thanks for the Maternal and Child Health Services Division,

National Health and Family Planning Commission.

This work was supported The research was supported by

Central Public-interest Scientific Institution Basal Research

Fund (2012GJSSJKC03).

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LOGO National Research Institute for Family Planning Preconception Blood Pressure and Risk of Preterm delivery in Chinese reproductive age women Yang Y,