Night Shift Among Women: Is It Associated With Difficulty Conceiving a First Birth?

Area of Science:

• Reproductive Science
• Chronobiology
• Occupational Health

Background:

• Circadian rhythm disruption impacts physiological systems, including female reproductive health.
• Night shift work is associated with potential reproductive issues like menstrual irregularity and endometriosis.

Purpose of the Study:

• To investigate the association between night shift work and the need for fertility treatment in women conceiving their first birth.
• To determine if night shift work is linked to specific infertility diagnoses.
• To examine age-specific relationships between night shift work and fertility treatment needs.

Main Methods:

• Retrospective data linkage study of 128,852 primiparous women in South Australia (1986-2002).
• Night shift work exposure assessed using a job-exposure matrix.
• Logistic regression analysis to assess associations, including age interactions and potential confounders.

Main Results:

• Women aged ≤35 years who worked night shifts were more likely to require fertility treatment (OR=1.40).
• No association was found between night shift work and fertility treatment need in women >35 years.
• Among women needing fertility treatment, night shift workers had higher rates of menstrual irregularity (OR=1.42) and endometriosis (OR=1.34).

Conclusions:

• Night shift work may contribute to an increased need for fertility treatment among younger women.
• This increased risk may be due to younger women's vulnerability to circadian disruption or work-related stress.
• Findings highlight potential reproductive health implications of night shift work for younger female populations.