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In today’s society, delayed marriage and childbirth have become common trends. While later marriage allows women more freedom to focus on personal growth, it also leads to a rising number of older pregnant women. Medical research shows that women aged 20 to 35 have the optimal fertility window, while pregnancies at age 35 or older are considered advanced maternal age. Older mothers face increased risks of pregnancy complications, congenital abnormalities, and higher miscarriage rates. For example, women under 30 have about a 15% chance of miscarriage, while for those over 40, the rate increases to 50%. Some women endure recurrent pregnancy loss, known as recurrent miscarriage, which brings significant physical and emotional challenges.
What is Recurrent Miscarriage?
Recurrent miscarriage is defined as having two or more consecutive pregnancy losses before 24 weeks gestation. Globally, about 1% to 2% of women experience recurrent miscarriage. In Hong Kong, approximately one in every hundred women faces this issue. Causes of recurrent miscarriage are diverse, including genetic defects, immune system disorders, uterine abnormalities, and chromosomal abnormalities in embryos.
Causes of Recurrent Miscarriage
Uterine Structural Abnormalities
Abnormalities such as congenital uterine malformations, endometriosis, fibroids, or uterine septum can interfere with proper embryo implantation and development, leading to miscarriage. Diagnostic tools such as pelvic ultrasound, hysterosalpingography, and MRI help evaluate uterine structure to prevent miscarriage.
Chromosomal Abnormalities
Chromosomal abnormalities are the leading cause of recurrent and early miscarriage, especially in older pregnant women. Studies show about 70% of miscarried embryos have chromosomal abnormalities, mostly numerical rather than structural. Such abnormalities are difficult to detect from parental appearance and require genetic testing. Even parents with normal chromosomes may produce embryos with abnormalities.
Immune System Disorders
Approximately 30% to 40% of recurrent miscarriage cases are linked to immune system dysfunction. The immune system protects the body, including the fetus during pregnancy. Women with autoimmune diseases such as lupus or clotting disorders are at higher risk for fetal growth problems and miscarriage.
Cervical Insufficiency
Cervical insufficiency occurs when the cervix is unable to stay closed during pregnancy, causing premature dilation and resulting in second-trimester miscarriage or preterm birth. It typically happens between 18 and 24 weeks gestation and may lead to uterine infection, further increasing miscarriage risk.
Endocrine Disorders
Hormonal imbalances such as thyroid dysfunction, abnormal prolactin levels, and polycystic ovary syndrome negatively affect pregnancy. These conditions may impair progesterone production or follicle maturation, raising miscarriage risk.
Psychological and Lifestyle Factors
Unhealthy habits like smoking, alcohol abuse, extreme dieting, and obesity increase the risk of recurrent miscarriage. Excessive stress, anxiety, and depression can also impact physiological functions and pregnancy outcomes.
Does Bleeding During Pregnancy Indicate Miscarriage?
About 20% to 40% of women experience bleeding in early pregnancy. Minor bleeding without uterine pain does not necessarily mean miscarriage; it can result from unstable embryo implantation or bleeding from blood vessels near the gestational sac. With rest and proper care, the pregnancy may continue normally. However, heavy bleeding resembling a menstrual period’s second day combined with severe abdominal pain may indicate miscarriage or ectopic pregnancy and requires prompt medical attention. Cervical polyps or abrasions can also cause bleeding during pregnancy and should be evaluated promptly.