Identical Twins - Does anyone know anything about the 'hook effect'?

[JessicaJones1]

Hi everyone.
I'm pregnant with identical twins and have spent the week very upset as my pregnancy tests have become incredibly weak (after being ridiculously strong). Someone advised me to Google the 'hook effect' and to try diluting my urine. So I did and here are the results! The top test is undiluted urine and the bottom ones are the same urine diluted bit by bit with water. As you can see, the more diluted my urine is, the stronger the test line gets. My mind is totally blown. Could this really be the hook effect? xx

Step away from the pregnancy tests.

I'm assuming that as you know it's twins you are far enough along to have had scans.

Why are you still testing? It means very little once you have got your BFP and had a scan.

Why do you need to do so many pregnancy tests?

I've never heard of it but why are you doing tests if you are pregnant. I only ever did one. Yes, I'm pregnant. Over.

Lol. I guess you guys all think I'm crazy? I'm 7 weeks today and last Friday I realised all my pregnancy symptoms had gone. So I took some tests to see if the lines were getting weaker and they were weaker than ever. I went to the EPU and had another emergency scan (we saw two strong heartbeats at 5 weeks btw). The sonographer could only find one heartbeat. He felt that there was a possibility one twin could be hidden behind the other. Following that the consultant advised us to prepare for the worst and got the counsellor to chat to us. The general consensus was that our outcome isn't going to be good. They told us to prepare for the worst and hope for the best. This was all based on one twin being missing on the scan, my pictures of my incredibly weak pregnancy tests and the fact that my pregnancy symptoms have all gone. Apparently the hook effect is a real thing and for those that understand it, they might be able to shed some light on my pic above. xx

It matches the descriptions I've read of the hook effect.

If not read too much into tests from now on though; it can be very confusing.

I can understand your worry regarding the second twin; please remember that some people will never know they had twins as it's common to loose one early and few people have these very early scans - but I do wish you the best and fingers crossed both beans grow well. Scans at this stage are difficult to always rely on too as the sonographer said.

Thee isn't a huge amount to understand with the Hook effect, the top and bottom of it is that pregnancy tests are designed to detect a particular hormone between a certain level. Over or under that level and the pregnancy test might not be as effective.

But the hospital should have been able to tell you from boood tests whether your level was falling or rising. Pee sticks aren't really a reliable way of testing for it. They literally just tell you if your pee contains the hormone or if it doesn't.

You really really can't set much store by symptoms either. In both my first pregnancy (miscarriage) and my second pregnancy (DC1) my symptoms came and went on roughly every two weeks, I would go from being extremely sick for 10 days abc then find girl a few days and then back to sick again. In my third pregnancy (DC2) I had hardly any symptoms at all.

Anyway, sorry to hear you are so anxious, I hope it all works out ok for you ?

But stop peeing on sticks, it won't help at all!

Thanks holycheeseplant. Like you said, it seems to be fairly common to lose one twin and never know.

My EPU didn't offer me any blood tests pastabest. I haven't had any at all. They scanned me at 5 weeks and saw 2 strong heartbeats and are scanning me every two weeks at least. So they're pretty good.

What you said about symptoms has reassured me a little too. I had a silent mc last September and knew it had happened as my symptoms disappeared overnight. I got a private scan which confirmed it and the measurements correlated with when I thought it had happened. (A few days before). I guess that's why I'm so anxious! Thanks for your reply. : )

I’ve read about the hook effect and considering your pregnancy tests are stronger when the urine is diluted suggests that is what is going on. (The hook effect) I’m sure that if you were losing one of the twins and your hcg had dropped slightly, then the test wouldn’t be stronger when it’s diluted. It would be weaker x

Hi MagicalCreatures. You are right, and these tests are 100% showing the hook effect, so it is a real thing!
Sadly a scan showed that one of the twins has gone but twin number 2 is still going strong. My hcg levels are too high to register properly on pregnancy tests without the urine being diluted. x

I have never heard of it but wanted you to know its quite common to lose one twin early on. I did with my second and went on to have a healthy baby. Its not nice but it happens sorry.

I'm sorry to hear that Congratulations on your little survivor!

Sorry to hear that OP but good luck with your little bean. X

Thank you everyone.
That's good to know Mindhunter. How lovely that you had a healthy baby. I'm so grateful to have one survive. It's nearly 11 weeks now! I've had 4 scans so far and all are looking great. : )