CAUSES OF FEMALE INFERTILITY
Understanding is the First Step to Clarity
Infertility is generally defined as the inability to achieve pregnancy after a year of regular, unprotected intercourse or after six months if the woman is over 35.
In women, fertility challenges can stem from a range of conditions that disrupt the natural steps of conception, from hormonal regulation to the structure of the reproductive organs. For pregnancy to occur, each stage from the release of an egg, its meeting with sperm, and successful implantation in the uterus needs to work together in harmony.
When any part of this process is interrupted, it may make conception more difficult.
Ovulation Disorders
One common group of infertility causes is ovulation disorders, where the ovaries do not release eggs regularly or sometimes not at all. These conditions are often associated with issues in hormonal regulation, specifically the hypothalamus and pituitary gland's control of reproductive hormones.
Polycystic Ovary Syndrome (PCOS) is the most common condition in this group, affecting both hormone balance and egg development.
Other factors, such as stress, significant weight changes, or excessive exercise, can disrupt the brain’s signals to the ovaries, leading to hypothalamic dysfunction.
Another cause is premature ovarian insufficiency (POI), where the ovaries lose their supply of eggs too early, often due to genetics, autoimmune conditions, or treatments such as chemotherapy. In women under 40, this leads to lower estrogen levels and the ovaries no longer producing eggs.
Elevated prolactin levels (hyperprolactinemia) can also disrupt ovulation, making it more difficult to conceive.
Without regular, healthy ovulation, the chances of natural conception are greatly reduced. Understanding and treating the underlying causes of ovulation disorders is key to improving fertility outcomes.
Tubal Infertility
Tubal infertility occurs when the fallopian tubes are blocked or damaged, disrupting the pathway for sperm to meet the egg or for a fertilised egg to travel to the uterus. Because this pathway is essential for natural conception, any obstruction in the fallopian tubes significantly reduces the chances of becoming pregnant.
One common cause is pelvic inflammatory disease (PID), an infection often linked to sexually transmitted infections such as chlamydia or gonorrhoea. If left untreated, PID can lead to inflammation, scarring, and blockages that interfere with the egg’s journey.
Damage may also occur following a ruptured appendix, which can cause pelvic infections affecting the reproductive organs, including the fallopian tubes. The resulting inflammation and scarring may create blockages that hinder natural conception.
In some cases, previous surgeries on the pelvic area — especially procedures to treat ectopic pregnancy — can leave behind scar tissue or adhesions. These changes may alter the normal anatomy of the reproductive organs, creating barriers that prevent sperm and egg from meeting.
While tubal infertility can feel discouraging, effective treatments are available. Surgery may sometimes be used to repair or unblock the tubes, while assisted reproductive technologies, such as in vitro fertilisation (IVF), offer an alternative by bypassing the fallopian tubes altogether.
Uterine & Cervical Causes
Uterine and cervical conditions can create physical barriers or unfavourable environments that make it harder for sperm and egg to meet, for an embryo to implant, or for a pregnancy to thrive. These issues, though varied, can significantly affect the chances of conception.
Uterine causes are often linked to changes in the structure or lining of the uterus. Benign growths such as fibroids and polyps can interfere with implantation. Depending on their size and location, fibroids may block the fallopian tubes or distort the uterine cavity, preventing the embryo from embedding and growing.
Some women are also born with congenital abnormalities of the uterus, such as a septate uterus (where a band of tissue divides the cavity) or a bicornuate uterus (where the uterus is heart-shaped). These differences can make implantation more difficult and increase the risk of miscarriage.
Other conditions can develop later in life. Asherman’s syndrome, for example, results from scar tissue forming inside the uterus, often after surgical procedures like dilation and curettage (D&C). This scarring can reduce the space available for implantation.
Chronic endometritis, a long-standing inflammation of the uterine lining often due to infection, may create an environment that is not supportive of embryo development. In some regions, diseases such as uterine tuberculosis can also contribute to infertility by damaging the uterine tissue.
Cervical causes relate to the narrow passage that connects the vagina and uterus.
Cervical stenosis, an abnormal narrowing or closure of this canal, can prevent sperm from entering the uterus altogether.
Even when the pathway is open, issues with cervical mucus may arise. Typically, around the time of ovulation, the mucus becomes thin and supportive, facilitating the passage of sperm toward the egg. If the mucus is too thick or hostile, it may act as a barrier instead.
While less common, cervical incompetence, where the cervix opens too early in pregnancy, can affect the ability to carry a pregnancy to term, linking cervical health to both fertility and pregnancy outcomes.
In many cases, medical or surgical interventions can improve fertility by correcting these uterine or cervical conditions, helping create a healthier environment for conception and pregnancy.
Endometriosis
Endometriosis is a chronic inflammatory condition where tissue similar to the lining of the uterus grows outside the uterine cavity. This misplaced tissue can cause pain, scarring, and adhesions that affect the ovaries, fallopian tubes, and uterus. While it is a common condition, its impact on fertility can be significant.
One of the main ways endometriosis interferes with conception is by distorting the normal anatomy of the reproductive organs. Adhesions and scar tissue may form around the ovaries, fallopian tubes, or uterus, making it more difficult for eggs to be released, transported, or implanted. In addition, the inflammation caused by the disease can impair the function of the fallopian tubes, reducing the chances that eggs and sperm will meet successfully.
Endometriosis is also linked to hormonal imbalances, particularly elevated estrogen levels, which can disrupt ovulation and affect egg quality. Beyond this, the condition can alter the immune system’s response within the pelvic cavity. Instead of supporting implantation, immune dysfunction may interfere with the embryo’s ability to attach and increase the risk of miscarriage.
Together, these factors create an environment that makes natural conception more difficult. However, many women with endometriosis do achieve pregnancy, and medical treatments — from surgical approaches to assisted reproductive technologies like IVF — can improve the chances of success.
Unexplained Infertility
Sometimes, even after thorough testing, no clear medical reason can be found to explain why pregnancy has not occurred. This is known as unexplained infertility and can account for a significant number of cases. For many couples, this diagnosis feels particularly frustrating because there is no obvious cause to address, yet the struggle to conceive remains very real.
Unexplained infertility does not mean there is no problem at all. Instead, it suggests that the issue lies in factors that are more subtle or harder to detect with current medical tests. These may include minor irregularities in ovulation, the quality of the eggs or sperm, challenges with fertilisation, or difficulties with embryo implantation. In some cases, the interaction between these factors may be the barrier, even if each one appears normal on its own.
The uncertainty of unexplained infertility can be emotionally taxing. However, it also means that many aspects of fertility are still functioning well, which is why many couples in this category go on to achieve pregnancy with the right guidance and support. Treatments may include lifestyle changes, fertility medications, intrauterine insemination (IUI), or in vitro fertilisation (IVF), depending on each couple’s circumstances.
Unexplained infertility is a reminder that fertility is a complex, delicate process. While answers are not always immediate, there are still many options to explore — and with expert care, many couples can move forward toward parenthood.
Lifestyle factors
Beyond specific medical conditions, certain well-known factors can affect a woman’s ability to conceive. Some, like age, are natural elements of life’s timeline, while others relate to health or lifestyle—many of which can be modified with the right guidance and support.
Age and Reproductive Health
Age remains the most significant risk factor for female fertility. Women over 35 experience a noticeable decline in both egg quantity and quality, which can make conception more difficult and increase the chances of miscarriage or pregnancy complications.
Weight and Metabolic Health
Fertility is sensitive to body weight. Both underweight and overweight women face increased odds of infertility. A balanced weight supports hormonal balance, regular menstrual cycles, and the effectiveness of fertility treatments.
Smoking
Current smoking has a well-documented negative impact on fertility. Studies show that women who smoke have around a 60% higher likelihood of infertility compared to non-smokers. Smoking accelerates egg ageing, disrupts hormone levels, harms ovarian reserve, and impairs uterine and tube function—while even past exposure in the womb may affect fertility later in life.
Alcohol Consumption
Health experts agree that no amount of alcohol is considered safe when trying to conceive or during pregnancy. Drinking can reduce the chances of conception, interfere with fertility treatments, and increase the risk of complications during pregnancy. For the best outcomes, it is recommended that women avoid alcohol altogether while planning for a baby and throughout pregnancy.
Other Health Conditions
Certain chronic or untreated medical issues—like thyroid disorders, diabetes, and hypertension—can subtly interfere with fertility. These conditions may affect hormone balance, menstrual cycles, and overall reproductive health, and are more commonly seen in women experiencing infertility.
