To evaluate the safety of working during pregnancyTo understand the laws concerning working in pregnancyin pregnancyTo evaluate the effects of standing, lifting and noise on pregnancy outcomesand noise on pregnancy outcomes.

Pregnancy Discrimination Act of 1978◦ Employer must offer same medical disability pay for◦ Employer must offer same medical disability pay for

pregnancy related disabilities as is offer for other disabilities.

Occupational Safety and Health Act (OSHA)p y ( )◦ Employer must provide a workplace free from hazardsFamily and Medical Leave Act (FLMA)◦ Public, private employers with 50 or more employees

k d lmust give 12 weeks or unpaid leaveBirth, adoption or foster care of a childWhen needed for spouse, child or parentWhen employee not able to perform job due to own healthWhen employee not able to perform job due to own health including maternity issues.

Right to work: 1991 Supreme Court ruling that make it illegal to ban women from certain jobs because they MIGHT become pregnant while working therepregnant while working there Right to disability benefits◦ Disability caused by pregnancy itself (nausea,Disability caused by pregnancy itself (nausea,

dizziness, swelling)◦ Disability cause by problems related to pregnancy

(infections preterm labor bleeding)(infections, preterm labor, bleeding)◦ Disability caused by job exposure (lead, toxic

agents)

Do I want to be pregnant ?Is the timing right for pregnancy ?Will my health be affected by the pregnancy?Will my baby be healthy ?Do I need to change habits before pregnancy?D I d i ti i t ?Do I need vaccinations prior to pregnancy?

Can I work during pregnancy? Yes Unless◦ Is your work very stressful?

Will you be exposed to dangerous chemicals?◦ Will you be exposed to dangerous chemicals?◦ Do you have underlying health problems that will

affect your pregnancy?◦ Have you had problems in a prior pregnancy?

Heavy liftingStanding or sitting or walking for long periods during the work dayCli bi b l i i kClimbing or balancing requirements at workExcessive heatExcessive stressExcessive stressOdors, especially during early pregnancy

Urinary catecholamines are higher in pregnant MDs, ICU nurses, during work days than off daysFollow up paper looking and comparing workFollow up paper looking and comparing work at hospital with control vs. no control and outcomesoutcomesComparison of active women vs. Dependent wives had more C/S, PTD, PIH, and IUGR.

Katz Obstet Gynecol 1991;77:338Magann Obstet Gynecol 1991;78:391

Work with strenuous activity, prolonged and repetitive lifting, prolonged standing◦ IUGR/SGA◦ Preterm labor and preterm delivery◦ Preterm labor and preterm deliveryNoise and pregnancy outcome is uncertainExposure to dangerous substancesExposure to dangerous substances◦ Chemotherapy◦ Lead, paint manufacturing, printing, pottery glazes,

b tt f t t ll b th kbattery manufactures, toll booth workers

Socioeconomic statusMaternal ageMaternal ageGravidity, parity, and prior abortionsRacePresence of prior PTD or IUGRPresence of prior PTD or IUGRPre-pregnancy weightWeight gain during pregnancyBleeding during pregnancyBleeding during pregnancyPrior history of pregnancy complications or adverse outcomesAlcohol consumption smoking drug useAlcohol consumption, smoking, drug use

Failure to take confounding variable into consideration could result in unpredictable and misleading conclusionsconclusions

Early studies from the French (1984-89) using Occupational Fatigue index linked higher scores withOccupational Fatigue index linked higher scores with greater risk of preterm birth (< 37 weeks) 8.3% vs. 2.7%◦ Standing: > 3 hours/day◦ Work on industrial machine: continuous / strenuous effort

and/or vibration◦ Physical exertion: Continuous vs. periodic, lifting/carrying

> 10 kilo, ,◦ Uncomfortable environment: Noise, cold, wet, manipulation

of chemical substancesStudies were not randomized, many variables not taken into consideration but lead to very lenient leavetaken into consideration but lead to very lenient leave policies in FranceMamelle AM J EPID 1984;119:309Manelle Paedia Perinat Wpidemiol 1989;3:705p ;

Study by Klebanoff evaluated both y yemployment and non-employment physical activity in 7100 women◦ Prolonged Standing (> 8 hours) PTD (OR 1.31)◦ Heavy work or exercise: PTD (OR 1.04)◦ Physical activity not linked IUGRPhysical activity not linked IUGRMost women with normal pregnancies are not at increased risk of PTD or IUGR based on employment or physical activity (confounding variables)

Klebanoff Am J Obstet G necol (NICHD)Klebanoff Am J Obstet Gynecol (NICHD)

Case – control study of 210 nurses with PTB vs. 1260 without PTB (7250 completed surveys) (42%)Occupational Fatigue Score (0 4)Occupational Fatigue Score (0-4)◦ Standing > 4 hour per shift◦ Tiresome effort (physical effort)(p y )◦ Mental stress (acute care or monitoring audio or

visual signalsEnvironment: cold anesthesia gases loud noises◦ Environment: cold, anesthesia gases, loud noises

Factors linked with PTB◦ Hours worked per week (p < 0.002)◦ Hours worked per shift (p<0.001)◦ Hours worked while standing (p < 0 001)◦ Hours worked while standing (p < 0.001)◦ Noise (p=0.005)◦ Physical exertion (p=0.001)◦ Occupational fatigue score (p<0.002)Adjusted OR were significant for hours worked per week and fatigue scoreworked per week and fatigue score

Luke, Keith, Manelle Am J Obstet Gynecol 1995;173:849-62

Date from Southhampton Women’s SurveyDate from Southhampton Women s Survey◦ 1327 pregnant women◦ 11-19-34 week interview (work hr, stand-walk-

squat-kneel – lift- night shift)q g )◦ Almost all work working 11 – 19 weeks (60%) at

34 weeksWorking women at 34 wk vs. those notWorking women at 34 wk vs. those not working◦ PTD: (OR .76, 95%CI 0.41,1.37)◦ SGA: (OR 1 25 95%CI 0 79 1 99)SGA: (OR 1.25 95%CI 0.79,1.99)◦ Small HC OR 1.04 95%CI 0.72,1.51) AC (OR1.21

95% CI 0.82,1.77) Bronzini OCC Environ Med 2009;66:685-90;

PTD: increased in women; sitting or standingPTD: increased in women; sitting or standing with trunk bent forward > 1 hr OR 2.92, 95% CI 1.27,6.7) other act NS, )Small HC in women work > 40 hr/weekMore studies need on trunk bending

Bronzini OCC Environ Med 2009;66:685-90

Nurses Health Study II◦ 110 000 women from 14 states ages 25-42 F/U◦ 110,000 women from 14 states, ages 25-42, F/U

questionnaire every 2 years◦ Overall response rate of 76%Work schedule◦ Days – evenings – nights – rotating night – rotation no

nights –◦ 1-20 hr / 20-40 hr / 40+ hrDefintionsDefintions◦ Lift > 25 pounds◦ Hrs/day stand or walk◦ Exposure of anesthetic gasesposu e o a est et c gases◦ Exposure sterilizing agents (gluteraldehyde – formalehyde –

ethylene oxideLawson AJOG 2009;200:e1-51.e8

PTD◦ Nurse work part-time (1-20 hr/wk)◦ decreased risk of PTD < 32 wk 30% not 32-36 wk◦ Night work and rotating work no link PTD◦ Night work and rotating work no link PTD◦ No association of > 40 hr/wk and PTD◦ Heavy lift, prolonged stand/walk no with PTDLawson AJOG 2009;200:e1-51.e8

Exposure to Sterilizing Agents◦ Exposure > 5 hr increase risk PTD 90% (also seen

in study with dental assist)◦ Anesthetic gases no increased risk◦ Anesthetic gases no increased risk64 with PTB < 32 weeks◦ Nurse work only nights increased risk 300%y g◦ No link with lifting, standing, exposure to

sterilizing agents or anesthetic gases.L AJOG 2009 200 1 51 8Lawson AJOG 2009;200:e1-51.e8

Prospective cohort study of 7135 working women evaluated by type of employment and working conditionsevaluated by type of employment and working conditionsBirthweight was decreased:◦ Workweek of > 32 hours◦ High job stress

High job stress + long work week (150 grams)◦ High job stress + long work week (150 grams)Avon Longitudinal Study (prospective cohort) of 9282◦ Absence of significance between job type birth weight◦ Metal workers, electrical workers, textile trade (jobs assembling j g

and working with equipment had lowest birthweights.

Vrijkotte AM J Public Health 2009;99:1409-16Farrow Occup Environ Med 1998;55:18-23

Daycare work: infection exposure, heavy lifting, noise, physically demanding postures◦ Risks for perinatal death, IUGR/SGA, PTB, Cong

anomaliesanomalies◦ 13,299 day care employees vs. 12,182 controls◦ Daycare workers are not at increased risk for

d i l di PTDadverse pregnancy outcomes including PTD, perinatal death, IUGR/SGA, or congenital anomalies

◦ Riipinen Scan J Work Environ Health 2009:DEC 14

Stress (high demand, low control)National Birth Cohort in Denmark◦ 33,694 daytime workers vs. 8075 shift workers

Analysis done by linkages of the National Registries◦ Analysis done by linkages of the National Registries◦ Fixed night work HR 1.85 95% CI (1.0-3.42)◦ No other shift work or job stress was linked with an

increased risk of stillbirth

Zhu J J Occup Environ Med 2004;46:1144-49Zhu J J Occup Environ Med. 2004;46:1144 49

Europop group (16 countries) employment and i k f bi hrisk of preterm birth◦ 5145 PTB, 7911 term births, of working women throught

3rd month of pregnancy◦ Overall no increased risk of PTB among working women

Working > 42 hr/week: OR1.33 (95% CI 1.1-1.6)Stand > 6 hr/day: OR 1.26 (95% CI 1.1-1.5)Stand > 6 hr/day: OR 1.26 (95% CI 1.1 1.5)Low job satisfaction: OR1.27 (95% CI 1.1-1.5)

Analysis of 4259 women in Demmark study PTDSt di d lki > 5 h /d OR 3 3 (95% CI 1 4 8)◦ Standing and walking > 5 hr/day: OR 3.3 (95% CI 1.4-8)

Saurel-Cubizolles J Epidemiol Comm Health 2003:58:395-401Henriksen TB Br J Obstet Gynaecol 1995;102:936-7

Nurses health study II: Prospective cohort study, 117,000 nurses, 14 states, questionnaire every 2 yr2 7 million nurses in US (50% reprod Age)2.7 million nurses in US (50% reprod. Age)14% of US work force (16 m) work even –night – irregular (30% in health professionsnight irregular (30% in health professions7688 women analyzed

◦ Whelan Epid 2007;18:350-55

68% days, 16% days/even, 9% night, 7% rotate nights, (18% worked > 40 hours)Results

D l i ht l RR 1 6 (95% CI 1 3 1 9)◦ Days only vs. night only : RR 1.6 (95% CI 1.3-1.9)◦ Rotating schedule: No increased risk◦ Work > 40 hr/week: RR 1.5 (95% CI 1.3-1.7)/ ( )◦ Early < 12 vs. Late 12-20 wk ab: no difference in

results except in day vs. day/evening RR 1.5 (95% CI 1 – 2 1)1 2.1)

Whelan Epid 2007;18:350-55

Excessive noise my interrupt normal fetal developmentWHO > 85 dB200 l d f i200 pregnant women evaluated for noise exposure (15 – 25 – 35 wk) during pregnancy and birth weightand birth weightDevice positioned on clothing at neck X 24H on workday onlyy y◦ No association was found with noise < 85 decibelsWu Am J Epid 1996;143:792-96

Heavy work and pregnancy: prolonged upright position and blood to exercising muscles may ↓ blood to exercising musclesAgricultural work in NE BrazilAgricultural work in NE Brazil ◦ 958 low-income women involved in sugar cane

production 56% →7 M, 40% → 8 M, 24% → 9 Mp◦ Heavy work for 9 months linked with a 117 gram

reduction in BW◦ Heavy work for < 9 months had no significant◦ Heavy work for < 9 months had no significant

effectInt J Epid 199;28:469-74

EF (Pat) Magann MDClinical Professor OB/GYN

University of Western AustraliafUniversity of Mississippi

Department of Obstetrics & Gynecology University of Western AustraliaDepartment of Obstetrics & Gynecology, University of Western AustraliaWomen and Infants Research Foundation, King Edward Memorial Hospital

Naval Medical Center, San Diego, Ca, USA

To evaluate the effects of standing, repetitiveTo evaluate the effects of standing, repetitive

lifting, and noise on maternal and perinatal

outcomes in a large low-risk healthy

population of working women

The proportion of women in the workforce has progressively increased over the past 50 years

Most women continue to work during pregnancypregnancy

Conflicting findings? increased risk of preterm delivery? increased risk of preterm delivery, low birth weight, IUGR associated with prolonged standing or heavywith prolonged standing or heavy lifting. ? impact of noise exposure on? impact of noise exposure on pregnancy outcomeReasons?Reasons?◦ Heterogeneous samples◦ Retrospective designsRetrospective designs◦ Confounding factors

Active-duty women attending the antenatal clinic at NMCSD (N = 814)◦ Active-duty women are an ideal group in which

to evaluate work related variablesRecruited at first antenatal visitRecruited at first antenatal visitAll subsequent antenatal visits and delivery took place at the NMCSDpExtensive questionnaires collected antenatal and postnatal information* The women could only alter their work environment if permission given by their

di fficommanding officer

StoodStood (hrs/d)(hrs/d) StoppedStopped (wks(wks))Stood Stood (hrs/d)(hrs/d) Stopped Stopped (wks(wks))

<4<4 <21<21<4<4 21 to 2821 to 28 3%

46%

<4<4 >28>284 to 84 to 8 <21<21

6%

21%

4 to 84 to 8 21 to 2821 to 284 to 84 to 8 >28>28 6%

5%

>8>8 <21<21>8>8 21 to 2821 to 28 2%

3%

9%

>8>8 >28>28 3%

LiftedLifted (hrs/d)(hrs/d) StoppedStopped (wks(wks))Lifted Lifted (hrs/d)(hrs/d) Stopped Stopped (wks(wks))

NoneNone<4<4 <21<21

70%

20%

<4<4 21 to 2821 to 28<4<4 >28>28 2%

2%

4+4+ <21<214+4+ 21+21+

4%1%

** Lifted weights > 11 kg

NoiseNoise StoppedStopped (wks(wks))NoiseNoise Stopped Stopped (wks(wks))

NoneNoneExposedExposed <21<21

75%

22%ppExposedExposed 21 to 2821 to 28ExposedExposed >28>28

1%

2%

* Noise exposure > 80 dB

• 270 (33%) women stood < 4 hrs/day for <21 wks, and did no lifting with no noise

Wide ariation in the intensit d ration and• Wide variation in the intensity, duration and combination of work activities in the remainder

Maternal DemographicsMaternal Demographics P ValuesP Values

N = 814N = 814 NN %% StandStand LiftLift NoiseNoise%%

Age (yrs) Age (yrs) mean (sd)mean (sd) 24.424.4 5.15.1 0.2040.204 0.0190.019 0.00010.0001

RaceRaceCaucasianCaucasianAfricanAfrican--AmericanAmerican

477477195195

58.658.624.024.0

0.5820.582 0.4900.490 0.4000.400

AfricanAfrican AmericanAmericanHispanicHispanicAsianAsianOtherOther

195195808045451717

24.024.09.89.85.55.52 12 1OtherOther 1717 2.12.1

Physical trainingPhysical training 498498 61.261.2 0.1560.156 0.5120.512 0.9320.932

Voluntary exerciseVoluntary exercise 549549 68.068.0 0.1400.140 0.7100.710 0.8760.876

Obstetric CharacteristicsObstetric Characteristics P ValuesP Values

N = 814N = 814 NN %% StandStand LiftLift NoiseNoise%%

GravidityGravidity11 435435 53.453.4

0.7960.796 0.2780.278 0.0610.06111223+3+

435435218218161161

53.453.426.826.819.819.8

ParityParity00 539539 66.266.2

0.4280.428 0.6580.658 0.0190.019

112+2+

2002007575

24.624.69.29.2

1Fraction still standing

0.8

0.6

0 2

0.4

<4 hrs

0

0.2 4-8 hrs>8 hrs p=0.0001

0 4 8 12 16 20 24 28 32 36 40

Gestational age at which standing altered (wks)

0

Hours/dayHours/day GA stopped GA stopped (wks)(wks)

Median (IQR) Median (IQR) (wks)(wks)

P P valuevalue(wks)(wks) (wks)(wks) valuevalue

0 0 -- 44 < 21< 21 39 (38, 4039 (38, 40+11)) 00..50250221 to 28 21 to 28 39 (39, 41)39 (39, 41)( , )( , )> 28> 28 3939+44 (38, 40(38, 40+22))

4 4 -- 88 < 21< 21 39 (3739 (37+11, 40, 40)) 0.6490.64921 to 28 21 to 28 39 (37, 39)39 (37, 39)> 28> 28 3939+66 (38, 40(38, 40+44))

>8>8 < 21< 21 39 (38, 40)39 (38, 40) 00.655.65521 to 28 21 to 28 39 (39, 41)39 (39, 41)> 28> 28 39 (38, 40)39 (38, 40)

Overall P value 0.069 (↓ 4 – 8 hours standing)

Hours/dayHours/day GA stopped GA stopped (wks)(wks)

Median (IQR) Median (IQR) (g)(g)

P P valuevalue(wks)(wks) (g)(g) valuevalue

0 0 -- 44 < 21< 21 3483 (3105, 3776)3483 (3105, 3776) 00..18218221 to 28 21 to 28 3448 (3148, 3858)3448 (3148, 3858)( , )( , )> 28> 28 3575 (3190, 4035) 3575 (3190, 4035)

4 4 -- 88 < 21< 21 3440 (3106, 3765)3440 (3106, 3765) 0.7630.76321 to 28 21 to 28 3295 (2864, 3705)3295 (2864, 3705)> 28> 28 3410 (2915, 3840)3410 (2915, 3840)

>8>8 < 21< 21 3385 (3023, 3901)3385 (3023, 3901) 00..99999921 to 28 21 to 28 3500 (3195, 3752)3500 (3195, 3752)> 28> 28 3730 (3068, 3885)3730 (3068, 3885)

Overall P value 0.684

30

%p = 0.012Preterm labour

25

30p = 0.126Preterm birth p=0.134

15

20 p=0.007 p=0.026

5

10

0

5

<4hr <4hr <4hr 4-8hr 4-8hr 4-8hr >8hr >8hr >8hr<21w <21w21-28w >28w21-28w 21-28w>28w >28w<21w

30

%p = 0.234Preterm labour

25

30p = 0.293Preterm birth

p=0.021

p=0.025

15

20p 0 0

5

10

0

5

None <4hr <4hr <4hr 4+hr 4+hr<21 wk 21-28 wk >28 wk 21+wk<21 wk

40

%p = 0.001Preterm labour

303540

p = 0.505Preterm birthp=0.0002

202530

p=0.132

101520

05

None < 21 w 21-28 w > 28 w

30

%

p=0.500

25

30

p=0.001

p 0.500

15

20p 0 00

10

0

5

Noisep = 0.130

Liftingp = 0.851

Standingp = 0.109

Standing > 4 hours/day

Women are more likely to alter their standing time during pregnancy

↑ Risk of preterm labour

↑ Ri k f t bi th↑ Risk of preterm birth

↑ Risk of IUGR (standing > 8hrs, stopping 21 k )wks)

Repetitive Heavy Lifting↑ Risk of preterm labour and preterm birth↑ Risk of preterm labour and preterm birth

Excessive and Prolonged Noise↑ Risk of preterm labour but not preterm birth

Clinical ImplicationsWomen should be advised to reduce their standing times during pregnancy and to avoid heavy lifting and exposure toavoid heavy lifting and exposure to prolonged and excessive noise

Exposure PTD LBW PIH

Systematic Review: 1966-2005: 53 reports indentified: 35 PTB, 34 LBW,9 PIH

Working hrs Small effect Moderate effect No effect

Shift Work Small effect No effect Moderate effect

Lifting Moderate effect No effect Limited data

Standing Small effect Moderate effect Moderate effect

Phy. Activity Studiesinconsistent

Moderate effect Limited data

Bronzi BMJ 2010; FEB 2