Lift testing of pregnant workers merits special attention in light of the possibilities of adverse maternal and fetal health consequences. For many years clinical management of pregnant workers for physical job activities relied on the AMA’s Council on Scientific Affairs published guidance on the effects of pregnancy on work performance (AMA, 1984). The AMA guidelines defined permissible limits that healthy employees with normal uncomplicated pregnancies should be able to perform without undue difficulty or risk of the pregnancy. According to this study lifting more than 51 lbs was permitted repetitively during the first half of pregnancy (up to week 20) and intermittently through week 30. After week 30 , intermittent lifting up to 24 lbs was permitted. Despite these recommendations, WorkSaver takes the position that these lifting recommendations are not valid as these values were not found to take into consideration all the variables of lifting as it relates to the recommended weight limit (RWL) determined by the NIOSH Lift Equation.
Should Lift & Carry Tests be Performed?
WorkSaver takes the position that a woman, while pregnant, should be considered temporarily disabled from lifting and carrying any substantial weight until she is no longer pregnant and as per the Pregnancy Discrimination Act (PDA), must be treated and protected the same as any other person who has temporary disability. In this regard, WorkSaver takes the position that lift and carry testing of pregnant women at any stage of pregnancy, should not be conducted for several reasons. First, there may be inadequate medical information available as to whether or not the pregnant woman has complications such as preeclampsia or cervical incompetence which make it unsafe to lift objects of any weight during pregnancy. Even if the pregnant worker is cleared to lift by a medical physician, there are valid concerns that may not have been considered by the medical practitioner related to increased risk of injury during lift testing of women during pregnancy. For example, using the NIOSH revised lift equation, recommended weight limits (RWLs) for pregnant women were analyzed by Waters et al. (Waters, et. al., Provisional Recommend Weight Limits for Manual Lifting During Pregnancy, Human Factors, 2014 Feb: 56(1):203-214) . Their revised guidelines advised against lifting any weight above the midshin or overhead. The RWL for lifts above the midshin and below overhead were considerably lower than 51 lbs during all stages of pregnancy and related to the type of lift actually required on the job.
Hormone Changes & Pregnancy
Fundamentally, hormonal and biomechanical changes during pregnancy increases the risk of injury during lifting while pregnant. Changes affect anthropometric characteristics such as an increase in overall body mass mainly in the upper body, changes in the center of gravity or mass, increased abdominal girth and changes in the spinal curvature such as excessive lumbar lordosis, In addition, hormonal changes cause an increase in joint laxity (Calguneri, et al, 1996) and potential spinal instability as well as changes in balance control (Whitcome, Shapiro, & Lieberman, 2007). Increasing the horizontal lifting distance (distance from the center of the lumbar disc L5-S1 to hand placement on the object being lifted) increases disc compression forces and increases the risk of a disc herniation or back strain/sprain.
The task parameter most directly influenced during the second half of pregnancy is the horizontal lifting distance. Anthropometric data on pregnant civilian and uniformed service women collected for the U.S. Air Force were used to estimate the minimum horizontal distance by gestation period (Perkins & Blackwell, 1998). At 20 weeks gestation, abdominal depth increases approximately 5 cm (about 2 inches) and as pregnancy advances to near full term (37-38 weeks), abdominal depth increase almost 14 cm or 5.5 inches. Accordingly, objects lifted in the later stages of pregnancy will be located farther from the spine, resulting in a larger horizontal moment arm. This translates into higher compression forces on the lower back. Mechanical compression , altered venous tone, and poor venous return for the lower extremities may be exacerbated by stooping to lift, inducing conditions of fetal hypoxia (Spinillo et al., 1996; Sternfeld, 1997) and low back pain (Noon & Hock, 2012).
Frequent or prolonged torso flexion is a significant risk for back injury and led to the American Conference of Governmental Industrial Hygienists (ACGIH) to set Lifting Threshold Limit Value of zero for most lifting from the floor (ACGIH, 2012). In addition, Bonzine et al (2009) and Florack et al, 1993 reported a nearly threefold increase of preterm labor and spontaneous abortion for women bending at the waist more than 1 hour per day. Avoidance of overhead lifting for pregnant women was recommended based on increased postural sway created by that activity which places too much of a load on the posterior elements of the lumbar spine (e.g., the facet joints).
Our Recommendation About Avoid Lift and Carry Testing
Due to the potential harm to the pregnant worker and fetus from lifting, employers are encouraged to avoid lift and carry testing of pregnant women upon hire and to place significant lifting restrictions on the employee after hire until the condition of pregnancy no longer exists. Lift and carry restrictions are a forms of accommodations which can improve the safety of the pregnant worker. After giving birth, the employee can be required to undergo a job-specific fit-for-duty testing to assess her lifting capacities prior to removing lifting restrictions. This will allow the employer to know determine if the employee has the abilities to perform job-specific lifting and carrying safely and whether or not accommodations will be needed.
Employers should become fully familiar with the Pregnancy Discrimination Act (PDA). A pregnant employee may be temporarily unable to perform all aspects of her job (e.g., lifting and carrying ) and as such is considered temporarily disabled. As such, the employer must treat her the same as any other temporarily disabled employee by providing reasonable accommodations such as light duty, restriction from lifting and carrying, modified tasks, alternative assignments etc.
For more information or a full citation of references listed, e-mail Dr. Bunch at Dr.Bunch@worksaversystems.com