Small-sized ‘gold standard’ copper intrauterine devices may have lower discontinuation and fewer side effects than standard-sized counterparts

By Hannat Akintomide

Pain and bleeding are the commonest unwanted effects of copper intrauterine contraception and pose barriers to continued use.

When choosing copper intrauterine contraception, the Faculty of Sexual and Reproductive Healthcare recommends a ‘gold standard’ intrauterine device (IUD). Gold standard IUDs are the most efficacious and have the longest duration of use. They contain at least 380mm2 of copper and have banded copper on the arms.

The most popular gold standard IUDs are the TT 380 Slimline® ( arm width 32 mm, stem length ≥33.6 mm)  and the T-safe 380A® and T-safe 380A QL® ( 32 mm x 35.95  mm), each licensed for 10 years of use.  The Mini TT 380 Slimline® is another gold standard IUD but is used less often. It is licensed for 5 years and measures 23.2 mm x 29.5 mm, making it significantly smaller both in arm width (8.8 mm shorter) and stem length (4.1-6.5 mm shorter). There is a paucity of research specifically on the Mini TT 380 Slimline® as well as a lack of research generally on the potential impact of IUD size on pain, bleeding and discontinuation.

Our retrospective study compared service documented user experiences and discontinuation in the first year following insertion of two gold standard IUDs of different sizes – the TT 380 Slimline (‘standard IUD’) and the Mini TT 380 Slimline (‘mini IUD’).

What we did

All retrievable service records of women who had had mini IUD insertions in one sexual health clinic between 1st October 2013 and 30th September 2016 were randomly 1:1 matched based on age with those of women who had had standard IUD insertions. Where a same age standard IUD comparator was not available, either a standard IUD insertion in a woman of the same age group was chosen for comparison, or no standard IUD comparator included if there was none available of the same age and age group. A total of 130 IUD users’ records were eligible for inclusion in this study – 67 mini IUD users and 63 standard IUD users.

Data from the first year following IUD insertion was collected. This included the users’ experiences, number of attendances, any follow up investigations as well as clinical findings. We also collected data on adverse events at the time of IUD insertion and removal. Records of women having a replacement IUD or one fitted for emergency contraception were excluded.

What we found

There was no significant difference between the standard IUD and mini IUD user groups based on age and uterine sounding length.  However there was a striking difference in discontinuation rates, particularly for pain and bleeding. Twice as many standard IUD users (n=20, 32%) discontinued compared to mini IUD users (n=10, 15%) at one year. Complaints of pain and bleeding were more likely to be reported in those requesting removal of the standard IUD (n=14, 70%) compared to those discontinuing their mini IUD (n=3, 30%). These differences were statistically significant and unrelated to parity.

More standard IUD users (n=24, 38%) attended in the first year for IUD related problems compared mini IUD users (n=16, 24%). Expulsions were also double in standard IUD users (n=4) compared to mini IUD users (n=2). All parous IUD users (n=3) who had experienced expulsions had had a standard IUD. The only pregnancy reported in the study sample was in a 30-year old parous standard IUD user 4 months after IUD insertion. The standard IUD had been inserted 8 months after her third vaginal delivery, with no IUD issues prior to pregnancy detection.

There was no statistically significant difference in discontinuation at one year based on parity. There was no difference between IUD users who had never been pregnant, had previous pregnancies but no births, or those who had previous birth(s) with regards to uterine sounding lengths, attendances, investigations requested or discontinuation at one year.

Possible limitations

These include the small sample size from a single service, the follow up period being one year, the tendency for standard IUD users to be of higher parity than their mini IUD-using counterparts, the reliance on coding to identify eligible records and the expectation that women would return to the same service for any IUD problems or removal.


More research on the different types and sizes of IUDs is needed to enable provision of the right IUD to the right patient, and to confirm our study findings. While randomised controlled trials could optimally determine the effect of gold standard IUD size on discontinuation rates, larger cohort and multicentre studies on gold standard IUDs of different sizes would also be useful.


Our retrospective review of two gold standard IUDs suggests that twice as many women will discontinue using a standard-sized gold standard IUD at one year compared to those who those using a small-sized gold standard IUD. Risks of pain, bleeding and expulsion also appear greater with the standard-sized IUD irrespective of parity.


Full Paper:

Akintomide H, Barnes P, Brima N, et al. Higher discontinuation rate with a standard-sized compared to a small-sized ‘gold standard’ copper intrauterine device: a case-control review. BMJ Sexual & Reproductive Health Published Online First: 04 September 2019. doi: 10.1136/bmjsrh-2018-200296

(Visited 15,519 times, 4 visits today)