Why am I not getting pregnant? The medical reasons couples struggle to conceive

By Sina Hartung, MMSC-BMI, Harvard Medical SchoolReviewed by Eureka Health Medical Group

Published: July 23, 2025Updated: July 23, 2025

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Key Takeaways

Trouble conceiving is usually due to ovulation disorders, male sperm problems, age-related egg decline, blocked tubes, or untreated health conditions such as thyroid disease or endometriosis. Lifestyle factors—weight, smoking, alcohol, and timing sex—add another layer. Knowing which cause applies often requires basic hormone panels, semen analysis, and pelvic imaging. Early evaluation after 12 months (6 months if the woman is 35+) prevents delays and guides treatment.

Which medical issues most often block conception?

Four out of every five couples who cannot conceive have one of five underlying causes. Pinpointing the exact problem lets doctors tailor treatment quickly. The team at Eureka Health notes that a simple work-up can identify the culprit in 80 % of cases.

Irregular or absent ovulation tops the listPolycystic ovary syndrome (PCOS) and thyroid imbalance explain about 25–30 % of female-factor infertility by disrupting monthly egg release.
Male sperm quality matters equallyLow count, poor movement, or abnormal shape account for roughly 35 % of infertility cases, yet many couples overlook a basic semen analysis.
Age-driven egg decline accelerates after 35By age 40 the chance of a healthy pregnancy per cycle falls below 10 %, mostly due to chromosomal errors in eggs.
Blocked or damaged fallopian tubes prevent the sperm–egg meetingPrior pelvic infections and endometriosis cause up to 20 % of tubal-factor infertility according to CDC data.
Uterine abnormalities can hinder implantationPolyps, fibroids bigger than 4 cm, or a uterine septum lower live-birth rates even with in-vitro fertilization (IVF).
Failure to ovulate drives 40 % of female infertilityThe NIH notes that disorders preventing regular egg release—such as PCOS or primary ovarian insufficiency—are responsible for about 40 % of female-factor infertility. (NIH)
Nearly 1 in 5 married U.S. women meet the definition of infertilityCDC data show 19 % of married women aged 15–49 with no prior births are unable to conceive after 12 months of unprotected sex, underscoring how common conception barriers are. (CDC)

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Which warning signs mean I should seek help sooner?

Some symptoms signal an urgent fertility evaluation rather than waiting a full year. Sina Hartung, MMSC-BMI, explains, “Early red flags let couples save precious time and, in many cases, reduce treatment intensity.”

Cycles shorter than 21 or longer than 35 daysHighly erratic periods suggest an ovulation disorder that may need medication or hormonal regulation.
Severe pelvic pain during periods or sexThis can be a clue to endometriosis, present in 30–50 % of women with infertility.
Two or more consecutive miscarriagesRecurrent loss might reflect hormonal, genetic, or immune issues requiring specialist testing.
History of pelvic inflammatory disease (PID)A single episode of PID can double the risk of blocked tubes, making early imaging essential.
Age 35–40 should prompt evaluation after 6 monthsGuidelines recommend women aged 35–40 see a fertility specialist if pregnancy has not occurred after six months of trying, while those over 40 are advised to begin testing right away. (Mayo)
Past chemotherapy or pelvic radiation warrants early screeningBecause cancer treatments can damage eggs or sperm, a history of chemotherapy or pelvic radiation is listed among reasons to seek fertility assessment without delay. (Mayo)

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How do female age and hidden conditions quietly reduce fertility?

Age isn’t the only silent factor; metabolic and autoimmune diseases also affect egg quality and implantation. The team at Eureka Health notes that identifying these health problems early can turn around fertility prospects.

Diminished ovarian reserve shows up as a low AMHAnti-Müllerian hormone (AMH) under 1 ng/mL often forecasts poor response to stimulation, prompting faster referral to IVF.
Uncontrolled thyroid disorders upset hormone balanceTSH above 2.5 mIU/L in women trying to conceive is linked to higher miscarriage rates.
Poorly managed diabetes harms both partnersMen with HbA1c >8 % have lower sperm motility, and women face more early miscarriages.
Celiac disease reduces absorption of fertility-critical nutrientsUntreated, it is present in up to 4 % of unexplained infertility cases but improves after a strict gluten-free diet.
Silent endometriosis can block conception without obvious painAround 20–25 % of endometriosis cases are "silent," and the resulting inflammation or ovarian endometriomas frequently underlie unexplained infertility, sometimes requiring IVF to achieve pregnancy. (DrSeckin)
Chromosomally normal embryos plummet after age 35Genetic testing shows about 75 % of embryos are chromosomally normal at age 25, roughly 50 % at 35, and only 10–15 % after 40, illustrating how age-related egg quality drives higher miscarriage and implantation failure rates. (NHF)

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Which lifestyle changes give the biggest fertility boost?

While medical treatment helps, everyday habits can move success rates by 10–20 %. “Small, targeted adjustments often tip the scales toward a positive test,” says Sina Hartung, MMSC-BMI.

Reach a body mass index (BMI) between 19 and 30Every 5-point BMI change away from this range lowers natural conception rates by about 8 %.
Quit smoking entirelyWomen who smoke need 1.6 times longer to conceive; male smoking cuts sperm count by up to 17 %.
Time intercourse to the fertile windowSex every 24–48 hours in the five days before ovulation yields pregnancy rates around 37 % per cycle versus 15 % with random timing.
Limit alcohol to no more than 7 drinks weeklyHigher intake is associated with a 30 % drop in IVF success for women and poorer sperm parameters in men.
Adequate sleep and stress managementSleeping 7–9 hours and using mindfulness lowered time-to-pregnancy by three months in a 2021 randomized trial.
Cap caffeine at under 200 mg dailyKaiser Permanente advises keeping daily caffeine below 200 mg when trying to conceive because higher intake is linked to reduced pregnancy odds. (Kaiser)
Aim for at least 2.5 hours of moderate exercise weeklyLogging 150 minutes of activity each week supports hormone regulation and can shorten time-to-pregnancy, according to Kaiser Permanente fertility guidance. (Kaiser)

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Which tests and treatments are the first step in a fertility work-up?

Basic investigations often reveal a quick fix, such as thyroid medication or antibiotics for infection. The team at Eureka Health recommends starting with low-cost tests before moving to IVF.

Day-3 FSH, LH, estradiol and AMH check ovarian reserveAn FSH above 10 IU/L or AMH below 1 suggests diminished reserve and guides urgency.
Transvaginal ultrasound and HSG map the uterus and tubesA hysterosalpingogram shows tubal blockage in 15 % of first-time infertility work-ups.
Semen analysis remains irreplaceableWHO standards classify normal count as at least 15 million sperm/mL; lower values shift focus to the male partner.
Ovulation induction with letrozole or clomiphene citrateThese oral medications restore ovulation in up to 80 % of PCOS patients under medical supervision.
Intrauterine insemination (IUI) before IVFFor mild male factor or unexplained cases, three cycles of IUI achieve pregnancy in about 20 % of couples.
Mid-luteal serum progesterone is a low-cost ovulation checkAAFP places a single day-21 progesterone draw among the first-line tests; a luteal-range result confirms that ovulation has occurred and can spare couples more invasive evaluations. (AAFP)
Early TSH and prolactin panels catch reversible endocrine causesCleveland Clinic highlights routine screening for thyroid-stimulating hormone and prolactin during the initial work-up because correcting hypo-/hyperthyroidism or hyperprolactinemia can rapidly restore fertility. (CC)

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How can Eureka’s AI guide your fertility investigation?

Eureka’s AI doctor reviews period logs, lab uploads, and semen reports to spot patterns a busy clinic might miss. “Our system flags thyroid issues or missed fertile windows within seconds, giving patients a clear next step,” explains the team at Eureka Health.

Automated fertile-window prediction with 95 % accuracyThe AI synthesizes cycle length, basal body temperature, and LH strips to suggest the exact two most fertile days.
Personalized lab recommendationsIf your cycles are irregular, the app may suggest AMH, TSH, and prolactin, which a physician reviewer can then order.
Real-time sperm quality dashboardMen can upload smartphone-assisted semen videos; the AI estimates motility and alerts if it falls below 40 %.

Getting started with Eureka’s private, free AI fertility coach

Eureka’s secure platform stores your health data privately, offers chat-based guidance, and can coordinate prescriptions after doctor review. Women using Eureka for fertility tracking rate the experience 4.7 out of 5 stars.

Symptom triage without judgmentAsk sensitive questions 24/7 and receive evidence-backed guidance in minutes.
Direct lab and imaging orderingWhen indicated, a licensed physician reviews the AI’s suggestion and can send an order to your local lab.
Progress tracking for both partnersCouples see combined charts of ovulation, semen quality, and lifestyle factors in one place.

Frequently Asked Questions

How long should we try before seeking infertility testing?

If the woman is under 35, see a clinician after 12 months; if 35 or older, go after 6 months, or sooner if periods are very irregular.

Does birth control use in the past delay fertility today?

Fertility returns to baseline within 1–3 months for pills and immediately for IUD removal, so prior contraception rarely causes lasting delays.

Can very light periods indicate a problem?

Yes. Short, scanty flow may mean inadequate uterine lining or ovulation issues and warrants hormone evaluation.

How accurate are at-home ovulation predictor kits?

LH urine strips predict ovulation about 12–36 hours ahead and are 80–90 % accurate when used daily around mid-cycle.

Is one blocked tube enough to stop pregnancy?

Not always. If the other tube is healthy, natural conception is still possible, but time to pregnancy may double.

Do supplements like folic acid improve fertility?

Folic acid prevents birth defects but doesn’t boost conception rates; however, women should still take 400 mcg daily before pregnancy.

Can mobile phone radiation lower sperm count?

Data are mixed, but keeping phones out of trouser pockets and using hands-free accessories is a reasonable precaution.

Will weight loss surgery help fertility?

In women with severe obesity, bariatric surgery often restores ovulation within 6–12 months, but pregnancy should wait until weight stabilizes.

How soon after a miscarriage can we try again?

Many clinicians allow trying after the first normal period, but waiting three months may be advised if complications occurred.

Does stress alone cause infertility?

High stress rarely causes infertility by itself, but it can alter hormone secretion and timing of intercourse, indirectly reducing chances.

References

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