It's Labor Day!

September 02, 2019

It's Labor Day!

In the United States, it's Labor Day, the day when we recognize and celebrate all workers for all that they have done for our country. 

As a Mom of 3 children, the word labor always brings up thoughts of childbirth so in an attempt to connect these two types of labors, I am sharing a paper I wrote awhile back that touches on work/labor and pregnant women (soon to be in labor) in the workplace.  While we think about all workers today and the impact that safety professionals have on keeping them safe, let's make sure we don't forget about workers who are also mothers-to-be.


The Pregnant Worker and Ergonomics

by Linda M. Tapp, ALCM, CSP

More than half of all American women work outside the home. In 1998, women accounted for 46.2 percent of the total workforce – a percentage that is expected to increase over time.  Assuming a 2 percent pregnancy rate and 50 million women of childbearing age, nearly one million working women may be pregnant at one time.

It is the employer’s responsibility to provide a safe and healthful workplace for all workers and all workers include pregnant women. With such a large number of employees that may become pregnant, is important to understand how pregnancy can impact workplace safety.  Often, discussion of risks related to pregnancy focus on chemical exposures but ergonomic concerns exist as well.

 For example, pregnancy can affect reach distance, balance and lifting tasks; It can also aggravate the affects of repetitive motion.  Some research also suggests a link between certain ergonomic stressors and adverse pregnancy outcomes, such a spontaneous abortion, pre-term delivery and low birth weight.  Several studies have found an increased risk of pre-term delivery among women whose jobs involve a combination of stressful factors, such a standing for long durations, repetitive lifting and working long hours. One study found elevated rates of stillbirths among leather workers, nursing assistants and others due to heavy lifting, physical exertion and long work hours. In a study of lawyers with degrees from the University of California atDavis, it was shown that (of this group) pregnant women that worked more than 45 hours per week were 5 times as likely to be stressed and three times as likely to have an early miscarriage. In this presentation we will examine ergonomic stressors in the workplace that may affect the pregnant worker. In addition, proactive steps safety professionals can take to minimize these hazards will be discussed.

 Most employers immediately consider the harmful effects of chemicals in the workplace when first notified of pregnancy.  In addition, many obstetricians will ask for a list of the chemicals that may present a risk of exposure to the pregnant employee but may not be as concerned with physical hazards. Ergonomic hazards such as awkward postures, heavy lifting, limited rest periods, and repetitive force also need to be considered.  Back pain and carpal tunnel syndrome are relatively common side effects of pregnancy as well, and both may be aggravated by job tasks.  In addition, the incidence of both may increase as pregnancy progresses.

 Pregnancy alters the body’s shape and, thus, the interaction with the work site. The abdomen becomes increasingly larger, causing progressive postural problems, backache, and impairment of dexterity, agility, coordination and balance.  Hormonal changes affect ligaments, increasing the likelihood of injury. Joints in the spine become less stable and show signs of separation and movement to accommodate the growing fetus.

As the pregnant workers body changes shape, new hazards related to reach, balance, lifting and repetitive motion may develop. Employers must be aware of these changes in order to continue to provide a safe, comfortable workplace.

Reach Distance

As  pregnancy progresses, a woman must lift and maneuver objects farther from her body. For example, an assembly line employee who has always had a comfortable reach of the 15 inches may have a 20 inch reach once into the third trimester due to the increased size of her abdomen. This places additional strain on the arms and shoulders as well as the lower back.  A study of working surface height and working surface areas showed that fit problems are likely during pregnancy.  In addition, few, if any anthropometric studies of pregnant women have been conducted, so it is difficult to find standardized information on appropriate workstation design.

Lifting loads farther from the spine is especially dangerous during this time because the woman’s muscles and ligaments are already being stressed beyond normal levels.  Pelvic muscles relax and spine joints become unstable, which only increases the risk of back injury.

These risks are most prominent during the third trimester, when the reach distance is greatest.  A woman lifting 10 pounds has about 65 pounds of pressure on her lower back.  When this woman is nine months pregnant, this task places approximately 150 pounds of pressure or her lower back due to the increased distance between the load of the body  (fig 1)


The extra weight a pregnant woman carries also affects balance.  In a non-pregnant woman, the center of gravity is located just in front of the spine and level with the kidneys.  Protrusion of the abdomen and the shift of the center of gravity increase the pregnant women’s chance of falling. Awkwardness, fatigue, and unstable footing resulting in a tendency to lose balance become critical when quick reaction time or work on elevated surfaces is required.  For example, work on platforms , ladders and/or slippery surfaces should be avoided. Additionally, if the work environment is hot, the pregnant woman is more likely to get dizzy, which can lead to falls and related injuries. Of course, the risk of greater injury is present when working from heights. The wearing of equipment harnesses or belts should not pose a danger if they do not place a great deal of pressure on the abdomen.

Lifting Tasks

Additional body weight and increased reach distance also impact lifting tasks.  When a pregnant employee bends over to pick up a box, she is not only lifting the weight of the box but her extra body weight as well. Depending on the size of the abdomen, she will likely be unable to hold the object close to the body. Lifting heavy weights is often thought to be the cause of back pain.  However, pregnant women may experience back pain even when their job involves little or no lifting.  According to some sources, up to 50 percent of pregnant women experience back pain regardless of their occupation. Many people associate back pain as the result of hard work. Many would also say that motherhood is the ultimate hard work so the fact that so many pregnant women experience it, is understandable.

There are three types of back pain associated with pregnancy; pain when sitting or standing; pain at the back of the pelvis and deep in the buttocks; and pain that occurs only when lying in bed. Back pain occurs because as the abdomen increases, the posture changes, which shifts the center of gravity and increases the amount of weight the pregnant women must bear. The hormone Relaxin is released in the body during pregnancy which is a good thing for delivery (it helps joints to be more flexible) but not so great for lower back pain since it decreases the stability of the lower back at a time it is under great stress. Further, the muscles of the abdomen are stretched out to accommodate the growing baby and can therefore no longer stabilize the pelvis.

Lifting may affect the pregnancy and fetus in several ways.  Muscular activity alters blood flow in the body, and circulatory blood flow in the uterus and placenta decreases while the woman is in a standing position. In addition, heavy lifting affects intra-abdominal pressures, which may provoke uterine contractions. Significant physical exertion may lead to hormone disturbances, hypothermia and nutritional deficits, all of which may have a negative affect on the fetus.

Pregnancy also changes the amount of weight and employee can lift safely. According to a study conducted by Texas University in 1988, which compared upper limb strength of pregnant and non-pregnant working women, non-pregnant working women were found to be significantly stronger.  The researchers concluded that this finding could have safety implications for the mother and fetus and, therefore should be considered in job assignment.  The American Medical Women’s Association suggests that risk management programs include a weight restriction for pregnant women of 25 pounds (10-12 kg).

It should be noted though that there is a movement away from rigid lifting weight guidelines and occupational physicians are being asked to first assess the pregnant worker’s baseline level of fitness and the ergonomic demands of the job. The ergonomic demands include the maximum amount of exertion required, the total duration of the shift and the frequency of breaks.  The occupational physician should also assess the obstetrical risk profile since intensive physical work has been associated with intrauterine growth retardation and pre-term birth. A high-risk woman (older, smoker, previous history of pregnancy problems) would need more work restrictions than a low risk woman who was very fit.


As pregnancy progresses into later stages, the curve in the lower back increases, which means the back muscles must work harder to help the woman maintain her balance. As a result, after standing for an extended period, the woman may experience lower back pain. Some studies have shown that prolonged standing is a serious pregnancy risk factor. A study of members of the Association of Women’ Health, Obstetric and Neonatal Nurses found that those who worked more than 36 hours per week, more than 10 hours per day, or who stood for more than 4 - 6 hours per day had an increased rate of pre-term deliveries.

Prolonged standing should be avoided, particularly in the third trimester when venous stasis is prevalent. (Prolonged sitting also causes venous stasis and the uterine bulk may also cause digestive upset. Therefore, changing from sitting to standing throughout the work shift should be encouraged.

Repetitive Motion

Carpal tunnel syndrome is a common side effect of pregnancy – approximately 28 percent of pregnant women experience it.  The extra fluid in the body can cause swollen feet, hands and legs; in hands and wrists, this extra fluid can compress the median nerve, producing carpal tunnel syndrome symptoms.  Most health practitioners would attribute this development to pregnancy rather than to work.  However, tasks that require repetitive motions may increase the possibility of developing the condition.  Fortunately, pregnancy related carpal tunnel syndrome usually disappears after the birth of the child.

Industry Challenges

While the challenge of maintaining an ergonomically correct workplace in manufacturing and office environments can often be met successfully, some industries – including the airline industry, health and government services – often have more difficulty accommodating pregnant workers, particularly in the third trimester, due to required daily tasks associated with jobs in those industries.

Airline industry

Many airlines “ground” female cabin crew staff after the first trimester because it is impossible to redesign the interior of an aircraft to accommodate a pregnant worker.  Flight attendants routinely help passengers lift heavy items into and out of overhead storage areas and push food and beverage carts (which weigh up to 143 pounds fully loaded) up an incline as the airplane climbs.  In addition, they’re responsible for passenger safety, a function that may include lifting heavy life rafts, opening cabin doors and sliding down chutes.  Although situations in which these tasks must be performed are rare, flight attendants must perform these activities during regular practice drills.

 U.S. Navy

Service women are another group whose routine tasks may be severely affected by pregnancy.  U.S. Navy Operational Obstetrics Policy states that for an uncomplicated pregnancy of physically fit, trained service women who works in a safe environment, there is a little need to restrict duty.  An “ergonomic restriction” would apply “where an individual’s physical configuration and/or disabilities preclude her from continuing with specific activities (such as lying in a prone position for weapons qualification, diving duty, attendant aboard ships, etc.) or where nausea or fatigability to work becomes the hazard”.  The Navy allows pregnant women to rest with their feet up for 20 minutes once every four hours; it also limits the employee to 40 hour workweek during the last three months of pregnancy.

Health-Care Industry

A union study found that 17 of 100 nursing home workers are hurt each year – with half of those incidents involving back injuries.  The Ontario Workplace Health and Safety Agency found that nurses and nursing aides are particularly susceptible to sprains and strains.  In many cases, the injuries are attributed to tasks that involve moving patients.

In addition, female positions have an increased risk of premature labor compared to the general population.  Some research suggests that this risk may be the result of long work hours and excessive standing.  Fifty percent of female physicians have their first baby during residency training while 25 percent have their second baby during this period.  Few medical schools have written policies regarding the health and safety of pregnant physicians or students.

Worker Rights in the US and Abroad

In the U.K., under the Control of Substances Hazardous to Health (COSHH) regulations, an employer must address any risk introduced during pregnancy. The regulations identify several physical hazards that may be cause for concern: handling, repetitive tasks, vibration, temperature extremes, ionizing radiation, work posture and travel.

The employer may adjust work conditions, work hours, or offer job transfer or paid leave. COSHH regulations also state that a new risk assessment (job analysis) must be performed whenever the workplace changes.  If elements of a particular job may pose a risk to the pregnancy, a formal risk assessment must be performed and appropriate corrective actions (in the form of workplace modifications) taken.  Under the European Directive on Pregnant Workers, an employer must provide a safe system of work to all women of reproductive age, their unborn children and working mothers whom breastfeed.  It suggests that facilities be provided in which pregnant women may rest (ideally, lying down).

In Sweden, a woman who performs physically heavy work has the right to receive a less strenuous job during the 60 days before her due date.  If not possible, she may receive paid leave (the same as sick leave).  In contrast, female employees in Mexico most show laboratory documentation stating whether they are pregnant when applying for a new job.  This is reportedly done to determine who will pay for the delivery.

Such a policy is a stark contrast to U.S. laws (such as Title VII of the Civil Rights Act of 1964) that make it illegal for employers to discriminate based on pregnancy in hiring, discharging and compensation, or in terms, conditions and privileges of employment.  Therefore, in the U.S., any modification or job transfer should be reviewed with the human resources department and/or legal counsel prior to its enactment.  Although the safety practitioner may have the employee’s best interests in mind, it is important not to violate her rights.

In the famous Johnson Controls case, it was argued that a gender defined fetal protection policy was reasonably necessary to the normal operations of the company and was a bona fide occupational exception to Title VII of the Civil Rights Act of 1964. The case came about when Johnson Controls required all non-sterile women of childbearing age to be forbidden from working in positions where there would be a likelihood of increased blood lead greater than 30 ug/dl and therefore a potential health risk to the unborn child. The Supreme Court found that "fetal protection policies" such as mandatory sterilization for women or complete exclusion from certain jobs are illegal gender-based employment discrimination and forbidden under Title VII of the 1964 Civil Rights Act.


Many firms have established ergonomic programs and strive to provide a comfortable, safe work environment for all employees. Designers typically attempt to create a workstation that will accommodate the smallest (5th percentile female) to the largest (95th percentile male) worker.  Adjustable workstations may meet the criteria – until a worker becomes pregnant.

In addition to work restrictions, the safety professional can implement several proactive steps to protect pregnant employees.  Each pregnancy is unique so care must be taken to match job requirements to the individual’s performance and capabilities.  All aspects of the job should be assessed when considering workplace modifications.

Potential Modifications

While application of sound ergonomic principles benefits all workers, the following actions can be considered when modifying a pregnant worker’s job.

  • Assign less physical tasks
  • Restrict lifting to 25 pounds
  • Adjust work (e.g., flexible scheduling, day shift rather than night)
  • Vary tasks to avoid static posture
  • Install foot rests (for seated and standing workers) so that one foot can be alternately raised
  • Adjust height of work surfaces and chairs. (Women late in pregnancy may prefer a considerably lower table height than common guideline heights)
  • Limit standing time to less than three hours a day.
  • Modify break schedule (e.g., shorter, more frequent breaks)
  • Reduce amount of work performed at heights (such as on ladders or steps tools).
  • Ensure good support is provided to the lower back for seated work
  • Provide chairs for seated workers that have a seat width, which allow semi-abduction of the legs with the feet flat on the floor.
  • Keep work areas as close as possible to the body
  • Adjustable seats
  • More space for moving around
  • Obstacles, particularly low objects should be avoided

 Further steps can be taken to help reduce the presence of back pain:

Inform employees to try to maintain good posture

Encourage employees to wear low-heeled (or no heeled) shoes.

Provide the best, ergonomically correct chair possible. The chair should have multiple controls that allow the user to adjust the back height, lumbar support, tilt, arm rest angle and height.

The American Medical Association (AMA) suggests that physicians encourage employers to accommodate a pregnant woman’s increased physical requirements including:

  • Modification of the work schedule to accommodate breaks every few hours
  • Encouraging and providing the opportunity for adequate hydration
  • Regularly varying work positions with sitting, standing and walking
  • Minimizing heavy lifting especially if associated with bending

One example of a successful ergonomic improvement can be seen in the Healthcare industry. In the health care industry, “zero-lift” programs have helped to reduce the number of back injuries. Within the healthcare industry, workers routinely lift and move patients whose weights are greater than the strengths of may workers. Lifting patients causes high compressive forces on the lower back. Add this to the fact that patients may be unpredictable in their movements that can cause unexpected stresses on the body. “Zero-lift” programs replace manual lifting of patients with battery operated hoists and other similar devices used for moving patients from one location to another.  These programs have been found to be highly successful. In one study including 7 nursing homes and one hospital, the number of injuries from patient transfers decreased by 86%.  This program not only helped all workers to have fewer back injuries but also allowed pregnant workers to stay on the job longer,

How Long Should the Pregnant Employee Work?

The following guidelines have been proposed. The length of time a pregnant woman is allowed to continue working is often a judgment call made by the women’s obstetrician. With every aspect of dealing with the pregnant worker, it is important to remember that each pregnancy and each woman is different and there are no cookie-cutter solutions to anything. By applying sound ergonomic principles, the safety practitioner will not only be helping to reduce workplace risks facing the pregnant woman, and possibly her unborn child, but will most likely be improving the workplace conditions for everyone.


Pregnant workers require extra attention with respect to potential ergonomic hazards that are either created or exacerbated by pregnancy.  Thus, when a pregnancy is first reported, the safety professional must work with the occupational nurse/physician, employee and her physician to assess these hazards. Appropriate accommodations can prevent injuries, enhance employee’s comfort, and help her better handle the stress of work combined with the physical changes related to pregnancy.




American Medical Association. Report 9 of the Council on Scientific Affairs (A-99): Effects of Work on Pregnancy,

American Medical Women’s Association. Position Paper on Pregnancy During Schooling, Training and Early Practice Years. Alexandria, VA: AMWA., 1993.

Atlanta Maternal – Fetal Medicine. “Restrictions for work and environment during pregnancy.” P.C.  Clinical Discussions.  Volume. 2, No. 6, July 19th, 1994.

Bauer, I. And T. Keupfer. :.  “Ergonomics and Pregnancy: Fact Sheet”, Toronto, Ontario: Occupational Health Clinics for Ontario Workers Inc., 1993.

Bodin, L., et al. :Heavy Lifting During Pregnancy: A Hazard to the Fetus?  A prospective study.”  International Journal of Epidemiology, 19 (1990): 90–97

Colliton, J., “Pregnant With Back Pain?  Suggested Comfort Tactics.”  The Physician and Sportsmedicine.  July 1996.

Eastman Kodak Co.  Ergonomic Design for People at Work.  Vol. 2, New York: Van Nostrand Reinhold, 1986.

Gabbel, S.G., “Work During Pregnancy: Potential Risks and Benefits.” OB./GYN Clinical Alert Archives, July 1999

 “Gender Specific Issues – An Industrial Hygiene Perspective”, The Synergist, Dec 2000, Vol 11, No 12

Goodwin, T., “Cabin Crew Maternity Policy: The Health and Safety Issues”, Aviation medicine.

 “Integrating Gender in Ergonomic Analysis: Strategies for transforming women’s work” – 1999, Edited by Karen Messing

Goulet, L. and G. Theriault.” Association Between Spontaneous Abortion and Ergonomic Factors: A Literature Review of the Epidemiologic Evidence” Scandinavian Journal of Work Environment and Health. 13(1987): 399–403

 Hagberg, W. “Carpal Tunnel Syndrome During Pregnancy.” Pregnancy Today Online.

 Henricksen, T. B., et al. “Standing at Work the Pre-term Delivery.” British Journal of Obstetrics and Gynecology.  102(1995): 198 – 206.

 Mamelle, N., et al. “Prematurity and Occupational Activity During Pregnancy.”  American Journal of Epidemiology.  119 1984: 309 – 322

Marbury, M.C., “Relationship of Ergonomic Stressors to Birthweight and Gestational Age.”Scandinavian Journal of Work Environment and Health.  18(1992): 73 – 83

Master, W.Y. and J.L. Smith, “Reaction Time and Strength in Pregnant and Nonpregnant Employed Women.”  Journal of Occupational Medicine.  1988.

Messing, K., “Women’s Occupational Health in Canada: A Critical Review snd Discussion of Current Issues.”

Misner, S.T., et al. “Women and Occupational Health

 “The Most Dangerous Job: Nursing.” CAW Health, Safety and Environmental Newsletter. Aug. 1997. http://www.

 Paull, J., et al.  “Pregnant Women and Working Surface Height and Working Surface Areas for Standing Manual Work.” Applied Ergonomics.  26(1995):129–133.

 Tapp, L., “Pregnancy and Ergonomics”, Professional Safety,August 2000, pages 29-32

U.S. Bureau of Labor Statistics.  Handbook of Labor Statistics.  Washington, D.C.: U.S. Department of Labor, 1998.

Virtual Naval Hospital.  “Operational Obstetrics and Gynecology: Appendix A Department of Navy, Bureau of Medical and Surgery, OPNAVINST 6000.1A Management of Pregnant Servicewomen.” Feb. 21, 1989.

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