A quantitative analysis of stored frozen surplus embryos in the UK

Figures & data

Figure 1. Number of IVF cycles over time by fresh and frozen embryos, 1991–2019.

Table 1. The number of embryos discarded by reason between 1991–2019, constructed based on the data provided by HFEA in August 2022. Blank spaces indicate that no data were available. Estimated total disposal in each year is calculated using Equation (1): $P_y=A_y+B_y+C_y+D_y+E_y+F_y$. *The data points ‘<5’ are averaged to 3 for expedience.

Year (y)	Withdrawal of consent (A)	End of storage period (B)	No longer required for use in treatment (C)	Donor samples discarded (D)	Found unsuitable for use in treatment (E)	Patient request (F)	Total embryos discarded (P)
1991
1992
1993
1994
1995
1996						3*	3*
1997
1998	6						6
1999	5						5
2000	36	17					53
2001	34	29				5	68
2002	87	24					111
2003	110	81					191
2004	128	49				6	183
2005	240	171				30	441
2006	297	256				13	566
2007	294	175				44	513
2008	330	299	3*			73	705
2009	1,629	796				110	2,535
2010	5,925	3,079				192	9,196
2011	6,379	4,371				245	10,995
2012	6,405	3,672			3*	437	10,517
2013	5,327	3,863	10	3*	30	2,961	12,194
2014	4,289	4,200	3*	5	417	2,902	11,816
2015	2,838	3,111	3*	18	1,124	3,683	10,777
2016	2,374	3,371	3*		1,441	4,741	11,930
2017	2,611	3,813			1,790	5,681	13,895
2018	2,979	8,881	3*	37	2,143	6,787	20,830
2019	2,769	6,989	3*	3*	2,417	7,360	19,541
Total	45,092	47,247	28	66	9,365	35,273	137,071

Figure 2. The estimated number of embryos in storage (U), embryo usage for treatment (J), yearly storage surplus (T), and new embryos stored (G), 1991–2019. The data were adopted from Table 2.

Figure 3. The rates of growth of estimated total in storage (calculated using Equation (4): $\mathrm{\delta U}=U_{y+1}-U_y$), embryo usage for treatment (calculated using Equation (5): $\mathrm{\delta J}=J_{y+1}-J_y$), and new embryos stored (calculated using Equation (6): $\mathrm{\delta G}=G_{y+1}-G_y$), 1991–2019. The data were derived from relevant data in Table 2.

Table 2. The number of embryos stored, donated, thawed, and discarded between 1991–2019, constructed based on the data provided by HFEA in August 2022. Blank spaces indicate that no data were available. The estimated yearly surplus is calculated using Equation (2): $T_y=G_y-H_y-I_y-J_y-P_y$. The estimated total embryos in storage at the end of each year is calculated using Equation (3): $U_{y+1}=U_y+T_{y+1}$. The U values are rounded up or down to the nearest thousand. *The data points ‘<5’ are averaged to 3 for expedience.

Year (y)	New embryos stored (G)	Embryosdonated to other patients (H)	Embryosdonated to research (I)	Embryos thawed during treatment (J)	Total embryos discarded (P)	Yearly storage surplus (T)	Estimated total in storage (U)
1991	4,957	61				4,896	5,000
1992	15,896	48				15,848	21,000
1993	19,737	56				19,681	40,000
1994	23,588	34	9	11		23,534	64,000
1995	32,490	44		6		32,440	96,000
1996	39,351	82	10	15	3*	39,241	136,000
1997	37,191	80				37,111	173,000
1998	42,780	146		58	6	42,570	215,000
1999	43,419	314	3,901	19,204	5	19,995	235,000
2000	47,921	276	5,258	26,339	53	15,995	251,000
2001	49,035	337	4,213	28,191	68	16,226	268,000
2002	45,785	191	4,501	29,679	111	11,303	279,000
2003	43,473	148	14,252	28,059	191	823	280,000
2004	44,593	213	17,925	28,160	183	−1,888	278,000
2005	45,723	199	10,019	28,665	441	6,399	284,000
2006	50,740	97	7,031	28,635	566	14,411	299,000
2007	48,765	106	10,062	30,126	513	7,958	307,000
2008	51,848	120	7,279	30,254	705	13,490	320,000
2009	50,954	106	5,699	31,995	2,535	10,619	331,000
2010	51,137	169	4,498	34,140	9,196	3,134	334,000
2011	50,604	101	2,659	33,754	10,995	3,095	337,000
2012	49,813	120	2,419	30,752	10,517	6,005	343,000
2013	60,212	126	1,645	32,134	12,194	14,113	357,000
2014	58,655	136	1,389	32,781	11,816	12,533	370,000
2015	70,514	167	1,368	34,490	10,777	23,712	393,000
2016	78,153	72	1,118	37,826	11,930	27,207	420,000
2017	84,885	196	1,105	39,775	13,895	29,914	45,000
2018	82,461	215	1,030	38,661	20,830	21,725	472,000
2019	90,012	209	675	40,360	19,541	29,227	501,000
Total	1,414,692	4,169	108,065	664,070	137,071	501,317	–

Note: As previously indicated, the HFEA emphasized that the data provided were from a live register and may not match data provided in previous requests or published elsewhere.¹¹

Figure 4. Number of donated embryos to other individuals from 1991–2019. The data were obtained from relevant date in Table 2.

Figure 5. Number of embryos donated to research from 1991–2019. The data were obtained from relevant date in Table 2.

Figure 6. The relative number of embryos donated to other patients (calculated using Equation (7): $\text{\%}H={\displaystyle \frac{H}{U}\times 100\text{\%}}$) and to research (calculated using Equation (8): $\text{\%}I={\displaystyle \frac{I}{U}\times 100\text{\%}}$) as percentages of the estimated total in storage (U) from the same year, 1991–2019. These data are derived from relevant data in Table 2.

Figure 7. The number of estimated total disposal, as well as disposal by various reasons listed, 1996–2019. The data were adopted from Table 1. The number of embryos discarded under the reasons ‘no longer required for use in treatment’ and ‘donor sample discarded’ are very small, so they are not plotted in this figure.