Ectopic Pregnancy Risk Factors, and Their Limits

An ectopic pregnancy is a pregnancy implanted outside the uterine cavity, most often in a fallopian tube, and it is a medical emergency: about 1% to 2% of US pregnancies, and 2.7% of pregnancy-related deaths. This page lists what raises the risk. It deliberately stops short of scoring it, for a reason set out below.

If you have severe pain, heavy bleeding, shoulder-tip pain, dizziness or fainting, seek emergency care now. Do not finish reading first.

The factors that raise the risk

Factor	What StatPearls reports
Previous ectopic pregnancy	About 10% recurrence after one, above 25% after two or more
Fallopian tube damage	From infection (gonorrhea, chlamydia), pelvic or tubal surgery, or endometriosis
Pelvic inflammatory disease	Including complications of ascending infection
Infertility and assisted reproduction	Higher with more embryos transferred, fresh rather than frozen transfers, and day-3 cleavage-stage transfers
Conception with an IUD in place	53% of pregnancies occurring with an IUD are ectopic
Progestin-only contraception	Slightly higher risk than other methods
Smoking	Through its effect on tubal function
Age over 35	Higher risk with advancing maternal age
Congenital anomalies of the reproductive tract	Anatomical variation may contribute

MedlinePlus adds scarring after a ruptured appendix, prior abdominal surgery, tubal ligation and surgery to reverse it, sexually transmitted infections, and some fertility treatments.

What is not on the list

Just as useful, and less often said. StatPearls states that oral contraceptives, a previous pregnancy termination, and failure of emergency contraception are not associated with an increased risk of ectopic pregnancy.

One caution about the source: the same chapter lists previous cesarean delivery as a risk factor in one paragraph and as not associated with increased risk in the next. Where a reference contradicts itself, the honest move is to say so rather than pick the half that reads better.

Why this page has no risk score

Because a score would answer a question nobody is actually asking.

Risk factors describe populations. They shift the prior probability across thousands of pregnancies; they do not classify the one in front of you. Two facts make that gap unbridgeable here. Most people with several factors on that table will never have an ectopic pregnancy. And ectopic pregnancies occur in people with none of them — MedlinePlus says outright that sometimes the cause is not known, and the implantations outside the tube are the ones least likely to fit the usual pattern at all.

What settles the diagnosis is imaging plus a hormone trend: transvaginal ultrasound alongside serial hCG. The discriminatory level, above which an intrauterine pregnancy should be visible on ultrasound, has historically sat between 1,000 and 2,000 mIU/mL, and ACOG has suggested a cutoff as high as 3,500 to avoid ending a viable pregnancy in error. For values under 1,500 mIU/mL, a rise below 49% over 48 hours, or a fall of 21% or more, argues against a normally progressing pregnancy. The wider context for those numbers is in hCG levels by week.

A number produced by a web page cannot participate in that. Worse, it can do harm in both directions: a reassuring output delaying a visit, or an alarming one arriving with no way to act on it.

What the risk factors are good for

One thing, and it is worth having: they lower the threshold for getting checked early.

If you have had a previous ectopic pregnancy, tubal surgery, pelvic inflammatory disease, or a positive test with an IUD in place, an early ultrasound to confirm the pregnancy is inside the uterus is a reasonable request rather than an anxious one. Tubal rupture rates around 15% have been reported in Western countries, and early detection is what keeps treatment conservative.

The signs that mean go now, regardless of risk factors

One-sided lower abdominal or pelvic pain, abnormal vaginal bleeding, pain at the tip of the shoulder, dizziness, fainting, or intense rectal pressure — in anyone with a positive test or who could be pregnant. Emergency departments report ectopic pregnancy in 6% to 16% of people presenting this way, which is why these symptoms are triaged rather than scheduled. They are described in full in ectopic pregnancy symptoms, and if you have not confirmed a pregnancy yet, see when to take a pregnancy test.

This content is informational. It does not diagnose, and no list of risk factors substitutes for evaluation by a clinician.