Fertility Awareness
vs
Sponge

A side-by-side comparison of two birth control methods — efficacy, cost, how they work, and who shouldn't use them.

Side-by-side comparison

Method
Fertility Awareness

Fertility Awareness

Tracking body signs like temperature and cervical mucus to identify fertile days and avoid unprotected sex then.
Sponge

Sponge

A soft foam disc placed deep in the vagina before sex. It covers the cervix and contains spermicide.
EfficacyLeast effective see details

Least effective: under 90 out of 100 people successfully prevent pregnancy per year.

Least effective see details

Least effective: under 90 out of 100 people successfully prevent pregnancy per year.

Cost$0–$100 /monthly

Insurance: Varies

$15–$20 /per package

Insurance: No

DurationOngoing daily trackingSingle use (can be left in place up to 24 hours and for multiple acts of sex)
ReversibilityReversibleReversible
STI ProtectionNoNo
How it works

Track basal body temperature, cervical mucus, and cycle length to identify the fertile window. Avoid unprotected sex or use backup contraception on fertile days.

A foam disc impregnated with spermicide is placed over the cervix before sex. The spermicide kills or disables sperm and the physical barrier blocks sperm from entering the uterus.

PrescriptionOTC No prescription / OTCOTC No prescription / OTC
Available Products4 products1 product
Side effectsNone reported
  • Vaginal irritation or dryness
  • Increased risk of urinary tract infection
  • Rare allergic reaction
Who shouldn't use this
  • Irregular cycles that make fertile window prediction unreliable
  • Inability to track consistently
  • Recent childbirth, breastfeeding, or perimenopause (cycles unstable)
  • Allergy to nonoxynol-9, benzalkonium chloride, or other spermicide ingredients
  • History of toxic shock syndrome
  • Active vaginal infection
  • Inability to insert or remove reliably
  • High risk of HIV exposure (frequent nonoxynol-9 use may increase vaginal irritation; CDC cautions)