What are the chances of having twins?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: August 31, 2025 • View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

Chances of Having Twins

The overall chance of having twins is approximately 1 in 30 births (about 3.3%) in the United States, with rates varying based on several factors including maternal characteristics and fertility treatment use. 1

Types of Twin Pregnancies and Their Frequency

Twin pregnancies are classified into two main categories:

Dizygotic (Fraternal) Twins

  • Result from fertilization of two separate eggs
  • Always dichorionic-diamniotic (two separate placentas and amniotic sacs)
  • Account for approximately 70% of all twin pregnancies
  • More common than monozygotic twins

Monozygotic (Identical) Twins

  • Result from division of a single fertilized egg
  • Can be:
    • Dichorionic-diamniotic (30% of monozygotic twins)
    • Monochorionic-diamniotic (70% of monozygotic twins)
    • Monochorionic-monoamniotic (1% of monozygotic twins)

Factors Affecting Twin Pregnancy Rates

Maternal Factors That Increase Chances

  • Family history: Women who are dizygotic twins themselves have a 30% higher risk of having twins 2
  • Advanced maternal age: Older women have higher rates of twinning
  • Higher parity: Women who have had previous pregnancies
  • Height: Taller women have increased risk of dizygotic twinning
  • Body mass index: Women with BMI >30 have greater risk of dizygotic twinning 3

Fertility Treatments

  • Major contributor to increased twin rates over the past decades
  • By 2011, approximately 36% of twin births and 77% of triplet and higher-order births resulted from fertility treatments 4
  • Two main types:
    • In vitro fertilization (IVF)
    • Non-IVF fertility treatments (ovulation induction)

Demographic Factors

  • Race: Black women have higher rates of twinning compared to white women 5
  • Geographic location: Twinning rates vary globally

Trends in Twin Birth Rates

  • Twin birth rates increased by a factor of 1.9 from 1971 to 2009 4
  • The rate increased from 1 in 53 births in 1980 to 1 in 30 births in 2009 6
  • This increase is largely attributable to:
    1. Increased use of fertility treatments
    2. Delayed parenthood (older maternal age)

Health Considerations for Twin Pregnancies

Twin pregnancies carry higher risks compared to singleton pregnancies:

  • 5-fold increase in fetal death
  • 7-fold increase in neonatal death
  • Higher risk of preterm birth, growth restriction, and congenital anomalies 1
  • Monochorionic twins have higher complication rates than dichorionic twins

Key Points to Remember

  • The chance of conceiving twins naturally is influenced by genetic factors, maternal age, and other biological characteristics
  • Fertility treatments significantly increase the likelihood of twin pregnancies
  • The risk of complications is higher in twin pregnancies, particularly monochorionic twins
  • Early determination of chorionicity is crucial for proper management of twin pregnancies
  • Multiple ultrasound examinations are typically required throughout twin pregnancies to monitor for complications 7

References

1
Guideline

Twin Pregnancies

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

3
Research

Dizygotic twinning.

Human reproduction update, 2008

4
Research

Fertility treatments and multiple births in the United States.

The New England journal of medicine, 2013

5
Research

Further defining the risks confronting twins.

American journal of obstetrics and gynecology, 1996

6
Research

How does the inclusion of twins conceived via fertility treatments influence the results of twin studies?

Twin research and human genetics : the official journal of the International Society for Twin Studies, 2012

7
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Related Questions

What are the risk factors for having twins?
What is the risk of having a twin pregnancy with a family history of twins?
Which Asian ethnic groups have a higher incidence of twinning (multiple gestations) due to genetic predisposition?
What can be used as an alternative to nifedipine (calcium channel blocker) for managing hypertension in patients experiencing peripheral edema (swelling)?
What is the prognosis for transverse myelitis?
Can acute pericarditis present with elevated troponin (cardiac biomarker) and B-type natriuretic peptide (BNP) levels?
Can ciclopirox (antifungal) topical be used in combination with griseofulvin (antifungal) to treat toenail fungus?
What are the causes and treatment options for transverse myelitis?
What should be avoided during pregnancy?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question