A late or missed menstrual period is often a source of worry, especially when contraception has been used. A period is considered late if it has not arrived within five to seven days of the expected date. This situation is common and can be attributed to many factors beyond pregnancy, even after protected sex. Understanding the reliability of contraception and exploring other physiological causes can help clarify the situation.
Understanding Protected Sex and Potential Failure
“Protected sex” usually refers to barrier methods, such as external or internal condoms, which physically prevent sperm from reaching the egg. When used perfectly, external condoms are highly effective, with a failure rate of about two percent over one year. However, human error is common, and the typical-use failure rate is considerably higher, ranging from 13 to 18 percent.
Failure often stems from mistakes made during use. Improper use, such as putting it on late, removing it too early, or failing to leave a reservoir tip, significantly reduces effectiveness. Condoms can also tear or break due to using oil-based lubricants, which degrade latex, or from improper storage in hot or high-friction environments. Checking the expiration date is important, as the material weakens over time, increasing the risk of mechanical failure.
Immediate Steps: When and How to Test for Pregnancy
If a period is late, the most definitive first step is a home pregnancy test. These tests detect human chorionic gonadotropin (hCG), a hormone released after a fertilized egg implants in the uterine wall. The concentration of hCG increases rapidly in early pregnancy, typically doubling every 48 to 72 hours.
For the most accurate result, test on the day of the missed period or at least 21 days after the possible conception event. Testing earlier can lead to a false negative because hCG levels may be too low to detect. Using the first morning urine is advised because it is typically the most concentrated sample. If the initial test is negative but the period still does not arrive, repeat the test a few days later or consult a healthcare provider for a blood test.
Non-Pregnancy Reasons for a Late Period
When pregnancy is ruled out, a late menstrual cycle is frequently caused by temporary disruptions to the hormonal signals that regulate ovulation. Significant psychological stress is a common culprit, as high levels of the stress hormone cortisol can interfere with signaling from the hypothalamus, which controls the menstrual cycle. This interference can delay or temporarily stop ovulation, pushing back the start date of the subsequent period.
Changes in body weight can also impact the menstrual cycle because a certain amount of body fat is necessary for the production of hormones like estrogen. Rapid weight loss or a low body-fat ratio can suppress reproductive hormone levels enough to prevent ovulation entirely, a condition known as functional hypothalamic amenorrhea. Conversely, significant weight gain or obesity can also cause hormonal imbalances that lead to irregular or absent periods.
Intense or excessive physical training, particularly high-intensity exercise, can mimic the effects of low body weight by creating a high-energy expenditure that signals a state of stress. This can result in a delayed or missed period as the body conserves energy. Furthermore, starting or stopping hormonal birth control, or changing other medications, can temporarily alter the hormone balance and shift the timing of the period.
Underlying medical conditions can also manifest as irregular or missed cycles. Polycystic Ovary Syndrome (PCOS) involves a hormonal imbalance where the ovaries produce excess androgens, often leading to irregular ovulation and missed periods. Thyroid imbalances, such as an overactive or underactive thyroid, regulate metabolism and can directly interfere with menstrual cycle regulation. These physiological factors demonstrate that a late period often points to a temporary or correctable change within the body’s complex system.